Endocrine recall practice
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Q36. A patient has episodic headache, sweating, palpitations and paroxysmal hypertension. Which investigation best establishes biochemical evidence of phaeochromocytoma?
Recorded recall sessions: April 2018; May 2022
A. Urinary cortisol alone
B. Thyroid-stimulating hormone
C. Serum aldosterone alone
D. Plasma free or 24-hour urinary fractionated metanephrines
Answer and explanation
D. Plasma free or 24-hour urinary fractionated metanephrines
Catecholamine-secreting chromaffin tumours produce metanephrines continuously, making plasma free or urinary fractionated metanephrines preferred sensitive biochemical tests. Imaging follows biochemical assessment unless an emergency dictates otherwise.
A. Investigates hypercortisolism, not catecholamine excess.
B. Investigates thyroid disease and does not confirm a catecholamine tumour.
C. Used in selected assessment of mineralocorticoid excess, not the described syndrome.
- Prepare confirmed functional tumours with alpha blockade before beta blockade
- Genetic evaluation is relevant in many patients
- Check medication and sampling factors that cause false positives.
Exam pearl: Phaeochromocytoma: metanephrines; alpha blockade before beta blockade.
Examiner trap: Old recalls favour urinary VMA, but modern metanephrine testing is more sensitive.
Viva extension: Why give alpha blockade before beta blockade? To avoid unopposed vasoconstriction and hypertensive crisis.
Q145. A patient is scheduled for right adrenalectomy for a phaeochromocytoma. Which major vessel lies anterior/anteromedial to the right adrenal gland and receives its short adrenal vein?
Recorded recall sessions: April 2021
A. Left renal vein
B. Portal vein
C. Inferior vena cava
D. Splenic vein
Answer and explanation
C. Inferior vena cava
The right adrenal gland lies close to the inferior vena cava; its short right adrenal vein drains directly into the IVC. This is a crucial operative hazard during right adrenalectomy.
A. The left adrenal vein usually drains to the left renal vein, not the short right adrenal vein.
B. The portal vein is not the immediate venous drainage recipient of the right adrenal gland.
D. The splenic vein runs posterior to the pancreas and is not a principal relation of the right adrenal gland.
- The right adrenal gland is related anteriorly to the liver and IVC.
- The left adrenal vein commonly joins the left renal vein.
- Phaeochromocytoma requires appropriate preoperative adrenergic preparation.
- Early identification of the short right adrenal vein helps avoid major haemorrhage.
Exam pearl: Right adrenal vein → IVC; left adrenal vein → left renal vein.
Examiner trap: Do not confuse the right adrenal gland’s relationship with the left-sided venous drainage pattern.
Viva extension: Which vein drains the right adrenal gland? A short vein directly into the IVC.
Q300. A patient has confirmed pituitary ACTH-dependent Cushing disease. Both adrenal glands are enlarged on imaging, without a discrete unilateral adrenal mass. Which histological process explains the adrenal enlargement?
Recorded recall sessions: September 2017
A. Unilateral adrenal cortical carcinoma
B. Bilateral adrenal cortical hyperplasia from chronic ACTH stimulation
C. Adrenal medullary pheochromocytoma
D. Adrenal cortical atrophy from ACTH deficiency
Answer and explanation
B. Bilateral adrenal cortical hyperplasia from chronic ACTH stimulation
Pituitary ACTH overproduction chronically stimulates the adrenal cortex, causing bilateral cortical hyperplasia and excess cortisol synthesis. The primary lesion is pituitary, not a unilateral adrenal cortisol-secreting tumour.
A. An adrenal carcinoma may autonomously secrete cortisol and suppress ACTH; it is not the expected bilateral response in pituitary Cushing disease.
C. A chromaffin tumour causes catecholamine excess and is not the cause of ACTH-driven bilateral cortical hyperplasia.
D. Reduced ACTH causes cortical atrophy, the opposite of the chronic stimulation described.
- Cushing disease specifically means pituitary ACTH excess.
- Cushing syndrome is the broader state of glucocorticoid excess from any cause.
- Exogenous glucocorticoids suppress ACTH and can cause adrenal atrophy.
- ACTH-dependent disease may cause bilateral adrenal hyperplasia.
Exam pearl: Pituitary ACTH excess -> bilateral adrenal cortical hyperplasia.
Examiner trap: Do not confuse Cushing disease with adrenal autonomous Cushing syndrome.
Viva extension: What happens to ACTH in exogenous steroid use? It is suppressed by negative feedback.
Q515. A patient with biochemically confirmed phaeochromocytoma is being prepared for elective adrenalectomy. Which preoperative sequence best prevents catecholamine-mediated haemodynamic crises?
Recorded recall sessions: January 2026
A. Begin propranolol, then add an alpha-blocker
B. Establish alpha-adrenergic blockade before adding beta-blockade if needed
C. Give beta-blockade alone until the day of surgery
D. Avoid alpha-blockade and rely only on intraoperative vasodilators
Answer and explanation
B. Establish alpha-adrenergic blockade before adding beta-blockade if needed
Alpha-blockade is established first to control catecholamine-induced vasoconstriction and permit volume expansion. Beta-blockade can then be added for persistent tachycardia after adequate alpha-blockade.
A. Starting beta-blockade first risks unopposed alpha-mediated vasoconstriction and severe hypertension.
C. Beta-blockade alone is unsafe in a catecholamine-secreting tumour.
D. Intraoperative rescue does not replace planned preoperative haemodynamic optimisation.
- Phenoxybenzamine or selective alpha-1 blockers are commonly used.
- Adequate salt and fluid intake may be required after alpha-blockade to correct contracted plasma volume.
- Beta-blockers are used only after alpha-blockade if tachycardia persists.
- Adrenalectomy is definitive treatment for suitable localised disease.
Exam pearl: Phaeochromocytoma: alpha first, beta second.
Examiner trap: Unopposed alpha stimulation after beta-blockade can precipitate hypertensive crisis.
Viva extension: Which biochemical tests establish the diagnosis? Plasma free metanephrines or fractionated urinary metanephrines, interpreted with appropriate sampling conditions.
Q753. A 58-year-old hypertensive man with chronic kidney disease starts losartan. Two weeks later, potassium rises from 4.5 to 5.8 mmol/L without ECG changes, while sodium remains normal. Which drug action best explains the rise in serum potassium?
Recorded recall sessions: September 2020
A. Blockade of angiotensin II AT1 receptors reduces aldosterone-mediated potassium secretion
B. Increased aldosterone release causes greater renal potassium retention
C. Direct stimulation of epithelial sodium channels in the collecting duct
D. Inhibition of carbonic anhydrase in the proximal tubule
Answer and explanation
A. Blockade of angiotensin II AT1 receptors reduces aldosterone-mediated potassium secretion
Losartan blocks angiotensin II AT1 receptors, reducing angiotensin II–stimulated aldosterone secretion. Reduced aldosterone action decreases distal nephron potassium excretion, particularly in patients with chronic kidney disease. The original recall included simultaneous hyponatraemia, which is not a reliable distinguishing feature of ARB therapy; sodium was normalised in this reconstruction.
B. Increased aldosterone usually increases distal potassium excretion, not retention.
C. ENaC stimulation increases the lumen-negative potential and generally favours potassium secretion.
D. Carbonic anhydrase inhibition is the mechanism of acetazolamide, not losartan.
- ARBs block the AT1 receptor; ACE inhibitors block conversion of angiotensin I to II.
- Both ACE inhibitors and ARBs can increase potassium, particularly with CKD or other potassium-raising drugs.
- Check potassium and creatinine after initiation or dose escalation according to clinical guidance.
- Hyponatraemia is not a defining diagnostic signature of an ARB.
Exam pearl: ARB → less aldosterone effect → less distal potassium secretion → hyperkalaemia risk.
Examiner trap: Do not assume hyperkalaemia plus hyponatraemia proves an ARB adverse effect; consider adrenal and renal pathology.
Viva extension: How do ACE inhibitors differ from ARBs in bradykinin effects? ACE inhibitors reduce bradykinin breakdown, whereas ARBs do not inhibit ACE.
Q916. A 38-year-old has episodic headaches, sweating and paroxysmal hypertension. Plasma free metanephrines are requested. Which sampling condition most reduces avoidable false-positive results?
Recorded recall sessions: April 2025
A. Collect immediately after vigorous exercise
B. Sample during a standing stress test
C. Give a beta blocker immediately before blood sampling
D. Allow the patient to rest supine before sampling and use supine reference intervals
Answer and explanation
D. Allow the patient to rest supine before sampling and use supine reference intervals
Plasma free metanephrines or urinary fractionated metanephrines are preferred first-line biochemical tests for phaeochromocytoma/paraganglioma. Plasma measurements should ideally be collected after quiet supine rest, with position-matched reference intervals, because upright posture and sympathetic activation can elevate normetanephrine and produce false positives. Medications, illness and analytical factors also affect interpretation.
A. Exercise can increase sympathetic activation and confound results.
B. Standing can increase measured normetanephrine and false positives.
C. Unselected beta blockade is not a sampling strategy and can be unsafe before alpha blockade in functional phaeochromocytoma.
- Preferred screening tests: plasma free or urinary fractionated metanephrines.
- Supine rest and matching reference intervals improve specificity.
- A positive test needs contextual interpretation and follow-up.
- Alpha blockade precedes beta blockade when preparing a functional tumour for surgery.
Exam pearl: Supine sampling is a test-quality issue in plasma metanephrine interpretation.
Examiner trap: Urinary VMA is less sensitive than fractionated metanephrines.
Viva extension: Why test metanephrines rather than episodic catecholamines? Intratumoral metabolism produces metanephrines continuously, even between attacks.
Q950. During a left laparoscopic adrenalectomy, the surgeon isolates the main left adrenal vein. Into which vessel does it normally drain?
Recorded recall sessions: April 2026
A. Inferior vena cava directly
B. Left renal vein
C. Splenic vein
D. Portal vein
Answer and explanation
B. Left renal vein
The left suprarenal vein typically drains into the left renal vein, often joining the left inferior phrenic vein before its entry. The right adrenal vein is short and drains directly into the inferior vena cava. This asymmetry is important during adrenalectomy.
A. Direct inferior vena caval drainage is characteristic of the right adrenal vein.
C. The splenic vein is a nearby pancreatic/splenic venous structure but not the usual principal left adrenal outflow.
D. The portal vein does not receive the normal main left adrenal vein.
- Right adrenal vein → IVC; left adrenal vein → left renal vein.
- The left adrenal gland is related anteriorly to the pancreatic body and tail.
- Adrenal veins should be carefully identified and controlled during adrenalectomy.
- The right adrenal vein is shorter and its direct IVC entry is a major surgical hazard.
Exam pearl: Left adrenal vein joins the left renal vein; right adrenal vein joins the IVC.
Examiner trap: Do not confuse the adrenal venous pattern with left and right gonadal veins, although both have a left renal vein connection.
Viva extension: What is the main arterial supply of the adrenal? Superior branches from inferior phrenic, middle from aorta, and inferior from renal artery.
Q37. A patient has recurrent exercise- or fasting-related sweating, confusion and faintness relieved by glucose. Which pancreatic endocrine tumour should be considered?
Recorded recall sessions: January 2016
A. Gastrinoma
B. VIPoma
C. Insulinoma
D. Glucagonoma
Answer and explanation
C. Insulinoma
Insulinoma secretes insulin inappropriately during hypoglycaemia. Whipple triad is symptoms compatible with hypoglycaemia, documented low plasma glucose and relief on correction.
A. Produces acid hypersecretion and ulceration rather than fasting hypoglycaemia.
B. Typically causes large-volume watery diarrhoea, hypokalaemia and achlorhydria.
D. Usually causes diabetes, weight loss and necrolytic migratory erythema.
- Biochemical confirmation may involve a supervised fast
- Assess insulin, C-peptide and proinsulin during hypoglycaemia
- Some insulinomas occur in MEN1.
Exam pearl: Fasting neuroglycopenic attacks relieved by glucose = insulinoma until excluded.
Examiner trap: Do not diagnose solely from symptoms without documenting plasma glucose.
Viva extension: What is Whipple triad? Symptoms, low glucose and symptom relief after glucose.
Q176. A 54-year-old man has recurrent fasting confusion and collapse relieved by glucose. During symptomatic hypoglycaemia, insulin is inappropriately elevated. Which additional finding supports endogenous insulin secretion from an insulinoma?
Recorded recall sessions: September 2018; May 2023
A. Suppressed C-peptide
B. Markedly raised CA 19-9
C. Raised C-peptide
D. High plasma glucose during symptoms
Answer and explanation
C. Raised C-peptide
Pancreatic beta cells release insulin and C-peptide in equimolar amounts when proinsulin is cleaved. Insulinoma produces endogenous hyperinsulinaemic hypoglycaemia with unsuppressed insulin, C-peptide and often proinsulin during a supervised fast.
A. This is more consistent with exogenous insulin administration when insulin is elevated.
B. CA 19-9 is not a biochemical marker of insulinoma and is used in other pancreaticobiliary contexts.
D. Whipple triad requires documented hypoglycaemia at the time of symptoms.
- Whipple triad: symptoms, documented low glucose, relief after glucose.
- Measure insulin, C-peptide, proinsulin and sulfonylurea screen during hypoglycaemia.
- Exogenous insulin typically suppresses C-peptide.
- Biochemical confirmation should precede localisation imaging.
Exam pearl: High insulin + high C-peptide during hypoglycaemia = endogenous hyperinsulinism.
Examiner trap: Sulfonylurea use can mimic insulinoma; perform a drug screen.
Viva extension: What distinguishes factitious insulin use? High insulin with suppressed C-peptide.
Q342. A woman with type 1 diabetes is receiving a variable-rate intravenous insulin infusion while fasting for emergency surgery. Which direct metabolic action of insulin occurs in skeletal muscle?
Recorded recall sessions: September 2020
A. Increased glycogen breakdown
B. Reduced GLUT4 translocation to the membrane
C. Increased release of potassium into plasma
D. Increased glucose uptake and glycogen synthesis
Answer and explanation
D. Increased glucose uptake and glycogen synthesis
Insulin promotes GLUT4 translocation in skeletal muscle and adipose tissue, increasing cellular glucose uptake. In muscle it activates glycogen synthase and favours glycogen storage. It also drives potassium into cells by stimulating Na+/K+-ATPase, which is clinically important during IV insulin administration.
A. Insulin inhibits glycogenolysis and promotes glycogen synthesis.
B. Insulin increases, not reduces, GLUT4 insertion into the cell membrane.
C. Insulin drives potassium into cells, so hypokalaemia may develop during infusion.
- Muscle and adipose glucose uptake is GLUT4 dependent.
- Hepatic glucose transport uses GLUT2 and is not directly GLUT4 dependent.
- Insulin suppresses lipolysis and ketogenesis.
- Monitor glucose and potassium during IV insulin treatment.
Exam pearl: Insulin increases skeletal muscle GLUT4 activity and glycogen synthesis.
Examiner trap: Insulin lowers serum potassium by intracellular shift, not urinary excretion.
Viva extension: Which transporter responds to insulin in skeletal muscle? GLUT4.
Q771. A 52-year-old man with calcific chronic pancreatitis and diabetes reports weight loss and bulky oily stools. Faecal elastase is 60 micrograms/g on a formed stool sample, and there is no bowel obstruction. What is the most appropriate specific nutritional treatment?
Recorded recall sessions: not recorded
A. High-dose systemic glucocorticoids
B. Total parenteral nutrition for every meal
C. Pancreatic enzyme replacement taken with meals and snacks
D. Complete long-term avoidance of dietary fat without enzyme therapy
Answer and explanation
C. Pancreatic enzyme replacement taken with meals and snacks
Faecal elastase below 100 micrograms/g in a suitable sample supports exocrine pancreatic insufficiency. Pancreatic enzyme replacement therapy (PERT) should be taken during meals and snacks to improve fat digestion, weight and fat-soluble vitamin status. AGA advice suggests an initial adult dose of at least 40,000 USP lipase units with each meal and about half with snacks, titrated to response.
A. Glucocorticoids are not routine treatment for exocrine insufficiency from calcific chronic pancreatitis.
B. Parenteral nutrition is reserved for special circumstances when adequate oral/enteral nutrition is not feasible; it is not standard first-line therapy.
D. Extreme fat restriction worsens nutritional risk and does not replace deficient digestive enzymes.
- Chronic pancreatitis is a major cause of pancreatic exocrine insufficiency.
- Faecal elastase below 100 micrograms/g strongly supports the diagnosis on formed stool.
- PERT is taken with food; adjust dose to meal size, fat content and clinical response.
- Monitor weight, steatorrhoea, fat-soluble vitamins and nutritional status.
- Enzyme replacement treats maldigestion but does not reverse chronic pancreatic structural damage.
Exam pearl: Chronic pancreatitis + steatorrhoea + low faecal elastase = PERT with meals.
Examiner trap: Do not use response to a short enzyme trial alone as a reliable diagnostic test for exocrine insufficiency.
Viva extension: What starting PERT dose is suggested for an adult? Approximately 40,000–50,000 USP units of lipase with meals and half with snacks, adjusted to clinical response.
Q788. A 24-year-old woman with a BMI of 13.5 kg/m² has had negligible food intake for three weeks. Two days after rapid initiation of nutritional support she develops weakness, tachycardia and respiratory difficulty; serum phosphate has fallen markedly. What is the most likely syndrome?
Recorded recall sessions: April 2021
A. Primary hyperparathyroidism
B. Hyperosmolar hyperglycaemic state
C. Acute intermittent porphyria
D. Refeeding syndrome
Answer and explanation
D. Refeeding syndrome
Reintroduction of carbohydrate stimulates insulin release and cellular uptake of phosphate, potassium and magnesium in a profoundly depleted patient. Severe hypophosphataemia can cause diaphragmatic weakness, cardiac dysfunction and arrhythmias. NICE classifies BMI below 14 kg/m² as an extreme-risk example, warranting very cautious energy initiation and close monitoring.
A. Primary hyperparathyroidism typically produces hypercalcaemia and is not triggered by restarting nutrition.
B. Hyperosmolar hyperglycaemic state requires marked hyperglycaemia and hyperosmolality, neither of which explains the classic post-feeding phosphate fall.
C. Acute intermittent porphyria causes neurovisceral attacks but not the characteristic electrolyte shift immediately after refeeding.
- Check phosphate, potassium and magnesium before and during nutritional rehabilitation.
- NICE advises around 5 kcal/kg/day initially in extreme-risk patients such as BMI below 14, with cardiac monitoring.
- Give thiamine before and during feeding and replace depleted electrolytes according to local protocols.
- Refeeding syndrome may manifest as respiratory failure, cardiac failure, arrhythmia or neurological deterioration.
Exam pearl: The hallmark of refeeding syndrome is a rapid fall in phosphate, often accompanied by low potassium and magnesium.
Examiner trap: Do not interpret a normal prefeeding serum phosphate as proof of normal total-body phosphate stores.
Viva extension: Why does serum phosphate fall? Insulin-driven intracellular phosphate uptake for ATP and phosphorylated intermediates during renewed anabolism.
Q978. A patient with severe hyperkalaemia receives intravenous soluble insulin together with glucose. Serum potassium falls within 30 minutes, before total-body potassium is removed. What mechanism best explains this effect?
Recorded recall sessions: September 2020
A. Increased urinary potassium excretion through immediate aldosterone release.
B. Direct binding and neutralisation of circulating potassium ions.
C. Inhibition of hepatic glycogen synthesis.
D. Stimulation of cellular Na+/K+-ATPase activity, moving potassium into cells.
Answer and explanation
D. Stimulation of cellular Na+/K+-ATPase activity, moving potassium into cells.
Insulin stimulates Na+/K+-ATPase in skeletal muscle and other tissues, rapidly redistributing potassium from extracellular fluid into cells. The effect is temporary and does not remove potassium from the body.
A. Insulin–glucose lowers potassium mainly by transcellular shift; urinary excretion is not the rapid primary mechanism.
B. Insulin does not chelate or bind potassium.
C. Insulin promotes, rather than inhibits, glycogen synthesis and this is not the mechanism of the potassium shift.
- Insulin promotes glycogen synthesis and inhibits hepatic glucose output.
- Give glucose and monitor capillary glucose to reduce hypoglycaemia risk.
- ECG changes or severe hyperkalaemia may require IV calcium for cardiac membrane stabilisation.
- Definitive potassium removal may require diuretics, binders or dialysis according to context.
Exam pearl: Insulin shifts potassium into cells; it does not eliminate it.
Examiner trap: Do not mistake ECG stabilisation with IV calcium for serum-potassium reduction.
Viva extension: Which other agent shifts potassium intracellularly? Nebulised beta-2 agonists such as salbutamol can provide an adjunctive shift.
Q218. An 8-year-old has a painless midline neck swelling just below the hyoid. It rises when the child swallows and protrudes the tongue. What is the most likely diagnosis?
Recorded recall sessions: September 2020; September 2021; 2021 (session not specified); May 2024
A. Branchial cleft cyst
B. Dermoid cyst
C. Cervical lymphadenopathy
D. Thyroglossal duct cyst
Answer and explanation
D. Thyroglossal duct cyst
A persistent embryological thyroglossal duct remnant forms a midline cyst connected to the tongue-base/hyoid region. Characteristic upward movement with tongue protrusion and swallowing helps distinguish it from other neck masses.
A. Branchial cleft cysts usually occur laterally near the anterior sternocleidomastoid border.
B. Dermoid cysts can be midline but typically do not move with tongue protrusion.
C. Lymph nodes do not characteristically move with tongue protrusion.
- Ultrasound confirms cystic nature and normally positioned thyroid tissue.
- Definitive operation is the Sistrunk procedure including the central hyoid segment.
- Infection should be treated before elective excision when feasible.
Exam pearl: Midline neck cyst moving with tongue protrusion = thyroglossal duct cyst.
Examiner trap: Ensure a normally located thyroid gland exists before excision.
Viva extension: Why is the central hyoid removed in Sistrunk surgery? To reduce recurrence from residual duct tissue.
Q228. A 52-year-old woman has a long-standing irregular multinodular thyroid enlargement with normal thyroid function. Histology shows variably sized follicles, colloid-rich nodules and areas of involution. Which process primarily underlies the development of a benign multinodular goitre?
Recorded recall sessions: January 2019
A. Primary squamous dysplasia of the follicular epithelium
B. Repeated cycles of follicular epithelial hyperplasia and involution
C. Diffuse malignant infiltration of the gland
D. Congenital hypoplasia of the thyroid gland
Answer and explanation
B. Repeated cycles of follicular epithelial hyperplasia and involution
Multinodular goitre develops through uneven follicular proliferation and subsequent colloid accumulation, haemorrhage, fibrosis and involution, producing nodules of different sizes and histological appearances.
A. Dysplasia is an atypical premalignant epithelial change, not the usual process of multinodular goitre.
C. Invasive neoplasia is not implied by benign, heterogeneous colloid-rich nodules.
D. Hypoplasia causes an underdeveloped gland, not acquired nodular enlargement.
- Follicular hyperplasia is not synonymous with malignancy.
- Long-standing goitres can show cystic degeneration, haemorrhage and fibrosis.
- Assess suspicious nodules using clinical and ultrasound risk stratification.
Exam pearl: Benign multinodular goitre = nodular hyperplasia with colloid and involution.
Examiner trap: Do not equate the term “nodule” with a clonal thyroid neoplasm.
Viva extension: Which histological changes can accompany long-standing multinodular goitre? Cystic change, haemorrhage, calcification and fibrosis.
Q307. During exploration for primary hyperparathyroidism, an inferior parathyroid gland is found adjacent to thymic tissue. From which embryological structure does the inferior parathyroid arise?
Recorded recall sessions: April 2021
A. Dorsal wing of the fourth pharyngeal pouch
B. Dorsal wing of the third pharyngeal pouch
C. Second pharyngeal cleft
D. Third pharyngeal arch mesenchyme
Answer and explanation
B. Dorsal wing of the third pharyngeal pouch
The dorsal part of the third pharyngeal pouch forms the inferior parathyroids and the ventral part forms the thymus. Their common descent explains ectopic inferior parathyroid tissue in or near the thymus.
A. The fourth pouch gives rise to the superior parathyroid glands.
C. The second cleft is an ectodermal groove and does not form the parathyroid glands.
D. The parathyroid epithelium is endodermal in origin from the third pouch, not arch mesenchyme.
- Superior parathyroids develop from the fourth pouch.
- Inferior glands have more variable positions because of longer embryonic migration.
- Ectopic parathyroid glands may be intrathymic or mediastinal.
- The thymus is derived from the ventral third pouch.
Exam pearl: Third pouch = inferior parathyroids + thymus.
Examiner trap: Do not confuse the numerical “inferior” gland with the fourth pouch.
Viva extension: Where may an ectopic inferior parathyroid be found? Along the thyrothymic tract or in the thymus.
Q317. A patient with a confirmed small-bowel neuroendocrine tumour develops episodic flushing, watery diarrhoea and wheeze. Which biochemical test best assesses serotonin overproduction?
Recorded recall sessions: September 2017
A. Serum amylase
B. Serum calcitonin
C. Urinary metanephrines
D. 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA)
Answer and explanation
D. 24-hour urinary 5-hydroxyindoleacetic acid (5-HIAA)
Serotonin is metabolised to 5-HIAA and excreted in urine. A properly collected 24-hour urinary 5-HIAA supports serotonin-secreting carcinoid syndrome, especially with flushing and secretory diarrhoea. Testing does not replace tumour staging or histopathology.
A. Amylase is a pancreatic and salivary enzyme, not a marker of serotonin metabolism.
B. Calcitonin is a marker for medullary thyroid carcinoma, not the usual marker for carcinoid syndrome.
C. Metanephrines are used for catecholamine-producing phaeochromocytoma and paraganglioma.
- Diet and medications can interfere with 5-HIAA measurement.
- Carcinoid syndrome often becomes clinically evident with hepatic metastases.
- Neuroendocrine tumours are graded using mitotic count and Ki-67.
- A large appendiceal neuroendocrine tumour needs oncological staging and operative review.
Exam pearl: Flushing + diarrhoea + NET = consider urinary 5-HIAA.
Examiner trap: The original 4-cm appendiceal tumour asks for “next investigation”; this educational reconstruction instead tests the specific serotonin biomarker.
Viva extension: Why are hepatic metastases associated with carcinoid syndrome? They bypass hepatic first-pass metabolism of vasoactive products.
Q474. A 54-year-old has a slowly enlarging thyroid swelling, mild tracheal deviation and a lower pole that cannot be palpated even during swallowing. Which diagnosis best explains this finding?
Recorded recall sessions: April 2025
A. Second branchial cleft cyst
B. Isolated cervical lymphadenopathy
C. Simple superficial dermoid cyst
D. Retrosternal (substernal) goitre
Answer and explanation
D. Retrosternal (substernal) goitre
An impalpable inferior thyroid border suggests extension below the thoracic inlet. Retrosternal goitres can displace or compress the trachea, and cross-sectional imaging helps define intrathoracic extent and operative anatomy.
A. This usually presents laterally along the anterior border of sternocleidomastoid.
B. A lymph node is not normally a diffuse thyroid-continuous mass with an impalpable lower thyroid pole.
C. A dermoid cyst is not continuous with thyroid tissue and does not characteristically extend beneath the sternum.
- Examine whether the swelling moves on swallowing.
- An impalpable lower border is a key clinical clue.
- CT helps assess tracheal compression and intrathoracic extension.
- Most retrosternal goitres can be removed through a cervical incision, depending on extent.
Exam pearl: Thyroid swelling with an impalpable inferior border suggests retrosternal extension.
Examiner trap: Not every impalpable lower border proves retrosternal extension; obesity and neck anatomy may limit examination.
Viva extension: What is Pemberton sign? Facial congestion or respiratory symptoms on arm elevation due to thoracic inlet obstruction.
Q490. A woman with longstanding skin hyperpigmentation presents with vomiting, profound hypotension, serum sodium 122 mmol/L and potassium 6.1 mmol/L. Adrenal crisis is suspected. Which treatment should be given immediately?
Recorded recall sessions: May 2022
A. Hydrocortisone 100 mg IV or IM with urgent isotonic saline resuscitation
B. Intramuscular adrenaline as the only treatment
C. Intravenous antihistamine alone
D. Wait for a short Synacthen test before treatment
Answer and explanation
A. Hydrocortisone 100 mg IV or IM with urgent isotonic saline resuscitation
Primary adrenal failure causes cortisol and aldosterone deficiency, leading to shock, hyponatraemia and hyperkalaemia. Suspected adrenal crisis is a time-critical emergency: give parenteral hydrocortisone promptly, restore circulating volume with 0.9% saline and treat precipitating illness.
B. Adrenaline treats anaphylaxis but does not replace missing glucocorticoid/mineralocorticoid activity.
C. Histamine blockade cannot reverse adrenal hormone deficiency or shock.
D. Diagnostic testing must not delay life-saving steroid and fluid treatment.
- Draw cortisol/ACTH before steroids only if this does not delay treatment.
- Primary adrenal failure often has hyperpigmentation from increased ACTH.
- Monitor glucose, potassium and fluid balance during resuscitation.
- Long-term primary adrenal insufficiency needs glucocorticoid and mineralocorticoid replacement.
Exam pearl: Suspected adrenal crisis: hydrocortisone 100 mg now; do not wait for tests.
Examiner trap: Hyponatraemia with hyperkalaemia suggests mineralocorticoid deficiency, unlike most secondary adrenal failure.
Viva extension: Why is hyperpigmentation present? Elevated ACTH/POMC-derived melanocortin signalling.
Q508. A 5-year-old has a recurrently infected midline neck cyst that moves with swallowing and tongue protrusion. Which operation best minimises recurrence after acute infection has settled?
Recorded recall sessions: January 2018; January 2025
A. Incision and drainage as definitive elective treatment
B. Simple cyst enucleation preserving the entire hyoid
C. Sistrunk procedure: excision of cyst, tract and central hyoid segment
D. Total thyroidectomy
Answer and explanation
C. Sistrunk procedure: excision of cyst, tract and central hyoid segment
Thyroglossal duct remnants often traverse or closely relate to the hyoid. The Sistrunk procedure removes the cyst, its tract and the central portion of the hyoid bone, reducing recurrence compared with simple cyst excision.
A. Drainage may be needed for acute abscess but leaves the epithelial tract and recurrence risk.
B. Failure to remove the tract and central hyoid increases recurrence.
D. A normal thyroid gland should not be removed for a benign thyroglossal duct cyst.
- A thyroglossal cyst typically moves with tongue protrusion.
- Confirm normal orthotopic thyroid tissue before surgery.
- Treat acute infection before elective Sistrunk surgery when feasible.
- A fistula can form after repeated infection or drainage.
Exam pearl: Sistrunk = cyst + duct tract + central hyoid.
Examiner trap: A midline neck cyst may contain the only functioning thyroid tissue; check anatomy before excision.
Viva extension: What is the embryological origin? Persistence of the thyroid descent tract from the foramen caecum.
Q559. A woman has recurrent fasting neuroglycopenic episodes with documented plasma glucose 2.3 mmol/L. During symptoms, insulin is inappropriately elevated. Which finding favours endogenous insulin secretion over injection of pharmaceutical insulin?
Recorded recall sessions: May 2022
A. Undetectable C-peptide
B. Low proinsulin
C. Suppressed beta-cell activity
D. Inappropriately elevated C-peptide
Answer and explanation
D. Inappropriately elevated C-peptide
Pancreatic beta cells cleave proinsulin into insulin and C-peptide, releasing both into circulation. Elevated C-peptide during hypoglycaemia supports endogenous hyperinsulinaemia such as insulinoma or sulfonylurea exposure, rather than exogenous insulin injection.
A. Undetectable C-peptide with high insulin suggests exogenous insulin administration.
B. Low proinsulin does not specifically confirm endogenous insulin secretion in this setting.
C. Suppressed beta-cell secretion contradicts the elevated endogenous insulin signal.
- Whipple triad: symptoms, low plasma glucose and relief after glucose.
- Measure glucose, insulin, C-peptide, proinsulin and sulfonylurea screen during an episode.
- Sulfonylureas also raise endogenous insulin and C-peptide.
- Biochemical confirmation precedes tumour-localising imaging.
Exam pearl: High insulin plus high C-peptide during hypoglycaemia indicates endogenous secretion, but exclude sulfonylureas.
Examiner trap: Do not label elevated C-peptide alone diagnostic of insulinoma.
Viva extension: How does exogenous insulin affect C-peptide? Insulin rises while C-peptide is typically suppressed.
Q637. A 56-year-old man presents with dehydration, confusion, abdominal discomfort and a corrected serum calcium of 3.6 mmol/L. He is haemodynamically stable and has no pulmonary oedema. What is the most appropriate immediate treatment?
Recorded recall sessions: May 2023; January 2024
A. Oral alendronate alone
B. Dexamethasone without fluids
C. Intravenous isotonic saline with ECG and renal monitoring
D. Immediate parathyroidectomy without stabilisation
Answer and explanation
C. Intravenous isotonic saline with ECG and renal monitoring
Severe symptomatic hypercalcaemia is an emergency. Restore intravascular volume with intravenous isotonic saline, assess ECG and renal function, identify the cause, and then use appropriate calcium-lowering agents (often an IV bisphosphonate or denosumab, with calcitonin for rapid short-term effect when needed). Fluids must be individualised in cardiac or renal failure.
A. Oral bisphosphonates are too slow and inappropriate as sole immediate resuscitation.
B. Glucocorticoids are useful in selected vitamin-D-mediated causes, not routine first-line monotherapy for undifferentiated severe hypercalcaemia.
D. Urgent definitive surgery is not the first action in a dehydrated symptomatic patient; stabilise and determine aetiology.
- Calcium above about 3.5 mmol/L with symptoms is potentially life-threatening.
- Assess volume status, ECG, electrolytes, creatinine, PTH and medication history.
- Isotonic saline is commonly the first intervention, adjusted for heart and kidney function.
- Calcitonin has rapid onset but tachyphylaxis; antiresorptives take longer to act.
Exam pearl: Hypercalcaemic crisis: volume resuscitation and monitoring precede slower calcium-lowering therapy.
Examiner trap: Do not give aggressive fixed-volume fluids without assessing heart failure or renal impairment.
Viva extension: How do PTH and PTHrP help? Suppressed PTH suggests a PTH-independent cause such as malignancy; inappropriately elevated PTH suggests primary/tertiary hyperparathyroidism.
Q678. A 64-year-old woman with a large multinodular goitre develops facial plethora, neck-vein distension and breathlessness when asked to raise both arms above her head. Which clinical sign is demonstrated?
Recorded recall sessions: January 2023
A. Trousseau sign
B. Chvostek sign
C. Kocher sign
D. Pemberton sign
Answer and explanation
D. Pemberton sign
Pemberton sign is elicited by arm elevation in patients with thoracic-inlet or superior mediastinal venous compression, classically from a retrosternal goitre. Raising the arms further crowds the thoracic inlet, causing facial congestion, venous distension and sometimes stridor or dyspnoea.
A. Trousseau sign is carpopedal spasm precipitated by a blood-pressure cuff in hypocalcaemia.
B. Chvostek sign is facial-muscle twitching after tapping the facial nerve, also associated with hypocalcaemia.
C. Kocher sign is classically associated with lid lag in thyrotoxicosis; it does not describe arm-induced facial congestion.
- Pemberton sign suggests thoracic-inlet venous obstruction rather than biochemical thyroid dysfunction.
- Assess for stridor, dysphagia, orthopnoea and positional dyspnoea.
- CT neck/chest helps delineate retrosternal extension and airway compression when indicated.
- Airway planning is important before surgery for a compressive goitre.
Exam pearl: Arms raised → facial plethora in retrosternal goitre = Pemberton sign.
Examiner trap: Do not confuse Pemberton sign with Trousseau sign: both are provocative but test entirely different physiology.
Viva extension: Why can retrosternal goitre cause stridor? The mass may compress or deviate the trachea at the thoracic inlet; chronic compression may coexist with tracheomalacia.
Q754. A woman develops perioral tingling after thyroid surgery. The examiner inflates a sphygmomanometer cuff above her systolic blood pressure for approximately three minutes. She develops wrist and metacarpophalangeal flexion with extension of the interphalangeal joints. Which bedside sign has been elicited?
Recorded recall sessions: January 2020
A. Chvostek sign
B. Trousseau syndrome of malignancy-associated thrombosis
C. Trousseau sign of latent tetany
D. Babinski sign
Answer and explanation
C. Trousseau sign of latent tetany
The Trousseau sign of latent tetany is carpopedal spasm induced by suprasystolic cuff inflation. It reflects neuromuscular hyperexcitability, commonly associated with low ionised calcium, although it is not perfectly specific. The original asked which finding was specific for hypocalcaemia, a non-defensible absolute claim; the reconstruction instead tests the manoeuvre and its interpretation.
A. Chvostek sign is facial muscle twitching after percussion over the facial nerve, not cuff-induced carpopedal spasm.
B. Trousseau syndrome is migratory thrombophlebitis associated with malignancy, not a tetany test.
D. Babinski sign is an extensor plantar response and reflects corticospinal tract dysfunction.
- Trousseau sign: suprasystolic cuff inflation for about 2–3 minutes causes carpopedal spasm.
- Chvostek sign: ipsilateral facial twitch after tapping the facial nerve.
- Trousseau sign is more specific for latent tetany than Chvostek sign but is not pathognomonic for hypocalcaemia.
- Check ionised or albumin-adjusted calcium and magnesium when tetany is suspected.
Exam pearl: Cuff-induced carpopedal spasm is Trousseau sign; facial twitching is Chvostek sign.
Examiner trap: Trousseau sign of tetany is not Trousseau syndrome of migratory thrombophlebitis.
Viva extension: Why does hypocalcaemia produce tetany? Reduced extracellular ionised calcium lowers the neuronal depolarisation threshold and increases neuromuscular excitability.
Q767. A 59-year-old smoker with a new small-cell lung carcinoma develops rapidly progressive proximal weakness, hypertension, hyperglycaemia and potassium 2.6 mmol/L. Blood gas shows metabolic alkalosis, and both ACTH and cortisol are markedly elevated. What is the most likely endocrine mechanism?
Recorded recall sessions: April 2019
A. Primary aldosterone deficiency
B. Primary adrenal insufficiency
C. Ectopic ACTH secretion producing severe cortisol excess
D. Isolated pituitary prolactin overproduction
Answer and explanation
C. Ectopic ACTH secretion producing severe cortisol excess
Small-cell lung carcinoma can secrete ACTH ectopically. Severe cortisol excess overwhelms 11-beta-HSD2 protection and activates mineralocorticoid receptors, increasing renal potassium and hydrogen-ion loss, causing hypokalaemic metabolic alkalosis. This pattern is especially striking in aggressive ectopic ACTH syndrome rather than being a universal laboratory feature of pituitary Cushing disease.
A. Aldosterone deficiency causes hyperkalaemia and often metabolic acidosis, not this pattern.
B. Adrenal insufficiency causes cortisol deficiency, hypotension and often hyperkalaemia in primary disease.
D. Prolactin excess does not explain markedly high ACTH/cortisol and severe hypokalaemic alkalosis.
- Ectopic ACTH is a cause of ACTH-dependent Cushing syndrome, often from thoracic neuroendocrine tumours.
- Severe hypokalaemia and metabolic alkalosis should raise suspicion for very high cortisol levels.
- Mineralocorticoid receptor activation from excess cortisol can occur despite suppressed aldosterone.
- Biochemical confirmation and localisation are required; urgent endocrine input is important.
Exam pearl: Small-cell lung cancer + ACTH excess + hypokalaemic alkalosis = consider ectopic ACTH syndrome.
Examiner trap: Hypokalaemia is not necessarily the most common laboratory finding in ordinary pituitary Cushing disease.
Viva extension: Why can cortisol cause mineralocorticoid effects? At very high concentrations it overwhelms renal 11-beta-HSD2, allowing cortisol to activate mineralocorticoid receptors.
Q850. A 9-year-old has a midline neck cyst that elevates with swallowing and tongue protrusion. A Sistrunk procedure is being considered. Which investigation is most useful before surgery to confirm a normally located thyroid gland and avoid removing the child’s only functioning thyroid tissue?
Recorded recall sessions: January 2025
A. Routine barium swallow
B. CT angiography of the carotids
C. High-resolution neck ultrasound including the thyroid bed
D. Immediate excision without preoperative imaging
Answer and explanation
C. High-resolution neck ultrasound including the thyroid bed
Ultrasound is the preferred first-line investigation for a suspected thyroglossal duct cyst. It characterises the cyst and demonstrates a normally situated thyroid gland, helping identify rare cases in which ectopic thyroid tissue may be the only functioning tissue. The definitive Sistrunk operation includes the cyst, tract and central hyoid segment when indicated.
A. Barium swallow does not establish whether normal thyroid tissue is present.
B. Carotid CT angiography is not the routine preoperative test for an uncomplicated thyroglossal duct cyst.
D. Proceeding without verifying thyroid tissue risks inadvertent removal of the only functioning gland in rare cases.
- A thyroglossal duct cyst commonly moves with tongue protrusion and swallowing.
- Ultrasound assesses the cyst and presence of orthotopic thyroid tissue.
- Simple cyst excision has higher recurrence than Sistrunk excision.
- Treat active infection before elective definitive surgery.
Exam pearl: Before Sistrunk, confirm that normal thyroid tissue exists in the thyroid bed.
Examiner trap: The source was an unreadable fragment. This distinct preoperative safety objective is not the existing question asking which operation to perform.
Viva extension: What does the Sistrunk procedure remove? Cyst, duct tract and central portion of the hyoid, with a suprahyoid core as appropriate.
Q896. A 40-year-old woman taking levothyroxine for autoimmune thyroiditis collapses with hypotension, nausea and marked buccal mucosal hyperpigmentation. Tests confirm low morning cortisol, high ACTH and a poor cortisol response to cosyntropin. Which unifying diagnosis is most likely?
Recorded recall sessions: not recorded
A. MEN type 2A
B. Isolated secondary adrenal insufficiency
C. Autoimmune polyglandular syndrome type 2
D. Cushing disease
Answer and explanation
C. Autoimmune polyglandular syndrome type 2
Autoimmune polyglandular syndrome type 2 combines primary autoimmune adrenal insufficiency (Addison disease) with autoimmune thyroid disease and/or type 1 diabetes. Primary adrenal failure raises ACTH and related melanocortin activity, explaining mucosal hyperpigmentation. Her acute hypotension is an adrenal emergency requiring immediate hydrocortisone and isotonic fluid resuscitation.
A. MEN2A features medullary thyroid carcinoma, phaeochromocytoma and sometimes primary hyperparathyroidism, not autoimmune thyroiditis with Addison disease.
B. Pituitary ACTH deficiency causes secondary adrenal insufficiency with low or inappropriately normal ACTH and generally no ACTH-driven pigmentation.
D. Cushing disease causes ACTH-dependent cortisol excess rather than low cortisol with shock.
- APS-2 requires autoimmune Addison disease plus autoimmune thyroid disease and/or type 1 diabetes.
- Primary adrenal failure typically causes raised ACTH, hyperpigmentation and often hyperkalaemia.
- Secondary adrenal failure generally preserves aldosterone and lacks prominent hyperpigmentation.
- Treat suspected adrenal crisis immediately; do not await confirmatory endocrine tests.
Exam pearl: Addison disease plus autoimmune thyroiditis strongly suggests APS type 2.
Examiner trap: Do not give thyroid hormone to an unrecognised cortisol-deficient patient without addressing adrenal insufficiency; it can precipitate crisis.
Viva extension: Viva: What is the immediate adult adrenal-crisis treatment? Hydrocortisone 100 mg IV/IM immediately with prompt 0.9% saline resuscitation, followed by stress-dose hydrocortisone and monitoring.
Q903. A 36-year-old woman has repeatedly raised adjusted calcium and inappropriately normal-to-high PTH. Her mother also has lifelong mild hypercalcaemia. Renal function and vitamin-D status are normal. Which investigation best helps distinguish familial hypocalciuric hypercalcaemia from primary hyperparathyroidism?
Recorded recall sessions: September 2020
A. Urinary calcium-to-creatinine clearance ratio
B. Serum amylase concentration
C. Chest radiograph
D. Fasting serum gastrin concentration
Answer and explanation
A. Urinary calcium-to-creatinine clearance ratio
Familial hypocalciuric hypercalcaemia (FHH) typically causes lifelong mild hypercalcaemia with relative hypocalciuria. A low urinary calcium-to-creatinine clearance ratio, classically below 0.01, favours FHH, although overlap exists with primary hyperparathyroidism. Family history, vitamin D status, renal function and sometimes genetic testing are needed for interpretation.
B. Amylase is not a discriminatory test between FHH and parathyroid-driven hypercalcaemia.
C. Chest radiography does not establish renal calcium handling.
D. Gastrin evaluates suspected gastrinoma and is not the relevant calcium-discrimination test.
- FHH is often caused by inactivating variants affecting the calcium-sensing receptor pathway.
- A clearance ratio below 0.01 favours FHH but is not absolute.
- Vitamin-D deficiency, CKD and thiazides can lower urinary calcium and confound interpretation.
- Parathyroidectomy usually does not correct FHH-associated hypercalcaemia.
Exam pearl: PTH-dependent hypercalcaemia with familial lifelong history: check urinary calcium before considering parathyroid surgery.
Examiner trap: Do not use a single low urinary-calcium ratio as proof of FHH without checking confounders and clinical context.
Viva extension: Viva: What is the key management implication of recognising FHH? Avoid unnecessary parathyroidectomy in an otherwise typical asymptomatic case.
Q904. A 60-year-old teacher has recurrent early-morning confusion, sweating and tremor that resolve after eating. During one episode, plasma glucose is documented at 2.2 mmol/L. An endogenous insulin-secreting tumour is suspected. Which supervised investigation is the standard diagnostic provocation test for fasting hypoglycaemia?
Recorded recall sessions: April 2021
A. Oral glucose tolerance test
B. ACTH stimulation test
C. Supervised fast of up to 72 hours with paired critical blood samples
D. Water-deprivation test
Answer and explanation
C. Supervised fast of up to 72 hours with paired critical blood samples
A supervised fast of up to 72 hours is the standard evaluation for suspected endogenous hyperinsulinaemic fasting hypoglycaemia. At the time of low plasma glucose, insulin, C-peptide, proinsulin, beta-hydroxybutyrate and a sulfonylurea/meglitinide screen help identify the mechanism. The test must be performed in an appropriately monitored setting.
A. An oral glucose tolerance test can provoke nonspecific symptoms and is not the preferred test for fasting insulinoma.
B. ACTH stimulation evaluates adrenal insufficiency rather than endogenous hyperinsulinaemia.
D. Water deprivation is used to investigate polyuria-polydipsia syndromes, not hypoglycaemia.
- Whipple triad requires compatible symptoms, documented low glucose and relief after glucose correction.
- The supervised fast may end before 72 hours when diagnostic hypoglycaemia occurs.
- High insulin with high C-peptide supports endogenous secretion; a drug screen helps exclude secretagogues.
- Low beta-hydroxybutyrate during hypoglycaemia supports insulin-mediated suppression of ketogenesis.
Exam pearl: Fasting neuroglycopenia with Whipple triad: collect critical samples during a supervised fast.
Examiner trap: Do not confuse a 72-hour supervised fast with an oral glucose tolerance test or with unmonitored home fasting.
Viva extension: Viva: How can sulfonylurea use mimic insulinoma? Both raise insulin and C-peptide; a positive sulfonylurea screen distinguishes secretagogue exposure.
Q938. A 40-year-old man has diffuse skin and palmar-crease hyperpigmentation, weight loss and salt craving before an elective operation. Postoperatively he develops profound hypotension, hyponatraemia and hyperkalaemia. Which underlying endocrine defect best explains the pigmentation and electrolyte pattern?
Recorded recall sessions: not recorded
A. Isolated secondary ACTH deficiency
B. Primary thyroid hormone deficiency
C. Isolated growth hormone deficiency
D. Primary adrenal cortical failure with elevated ACTH
Answer and explanation
D. Primary adrenal cortical failure with elevated ACTH
Primary adrenal insufficiency causes deficient cortisol and aldosterone, leading to hypotension, hyponatraemia and often hyperkalaemia. Loss of cortisol feedback elevates ACTH and related POMC peptides, contributing to hyperpigmentation. Suspected adrenal crisis requires immediate hydrocortisone and isotonic saline, without waiting for confirmatory testing.
A. Secondary ACTH deficiency generally lacks ACTH-driven pigmentation and usually preserves aldosterone secretion.
B. Hypothyroidism does not explain this combination of pigmentation, salt craving and hyperkalaemic shock.
C. Growth hormone deficiency is not the cause of acute mineralocorticoid failure.
- Primary adrenal insufficiency: low cortisol, high ACTH, often low aldosterone.
- Hyperpigmentation suggests increased ACTH/POMC activity.
- Stress from surgery may precipitate crisis.
- Give immediate parenteral hydrocortisone and saline when crisis is suspected.
Exam pearl: Hyperpigmentation plus hyperkalaemia points to primary rather than secondary adrenal insufficiency.
Examiner trap: The question asks the underlying defect; do not delay emergency steroid therapy while pursuing the diagnosis.
Viva extension: Viva: What emergency dose is recommended in adults? Hydrocortisone 100 mg IV/IM immediately, then 200 mg over 24 hours or 50 mg every six hours with fluids.
Q38. After kidney transplantation, a patient has persistent very high PTH, hypercalcaemia, hypophosphataemia and bone pain. What is the likely diagnosis?
Recorded recall sessions: January 2017
A. Secondary hyperparathyroidism with uncomplicated hypocalcaemia
B. Vitamin D deficiency alone
C. Tertiary hyperparathyroidism
D. Isolated hypoparathyroidism
Answer and explanation
C. Tertiary hyperparathyroidism
Long-standing renal secondary hyperparathyroidism may progress to autonomous parathyroid overactivity, persisting after renal transplantation and leading to hypercalcaemia and bone disease.
A. Usually results from chronic kidney disease with compensatory elevated PTH and often low/normal calcium.
B. Does not typically produce autonomous high PTH with hypercalcaemia after transplantation.
D. Causes low PTH and hypocalcaemia.
- Check PTH, phosphate, vitamin D and renal function
- Management may include calcimimetic therapy or parathyroidectomy
- Bone turnover abnormalities may persist after transplantation.
Exam pearl: Autonomous PTH with post-transplant hypercalcaemia = tertiary hyperparathyroidism.
Examiner trap: Secondary and tertiary hyperparathyroidism are distinguished partly by autonomy and calcium status.
Viva extension: How does PTH affect phosphate? Promotes renal phosphate excretion.
Q39. During parathyroid surgery, which artery supplies most parathyroid glands?
Recorded recall sessions: January 2024
A. Facial artery
B. Inferior thyroid artery
C. Lingual artery
D. External carotid artery directly in most patients
Answer and explanation
B. Inferior thyroid artery
Both superior and inferior parathyroid glands commonly receive arterial supply from branches of the inferior thyroid artery, although variation and contributions from superior thyroid branches exist.
A. Supplies facial structures, not parathyroids.
C. Supplies the tongue and floor of the mouth.
D. Parathyroid blood supply is primarily via thyroid arterial branches rather than a direct external carotid branch.
- Preserve glandular vascular pedicles during thyroidectomy
- Devascularisation can cause postoperative hypoparathyroidism
- Superior glands derive embryologically from fourth pouches and inferior glands from third pouches.
Exam pearl: Inferior thyroid artery commonly supplies the parathyroids.
Examiner trap: Inferior parathyroid glands migrate with thymus and may be ectopic.
Viva extension: Which nerve is anatomically close to inferior thyroid vessels? Recurrent laryngeal nerve.
Q83. A patient with longstanding chronic kidney disease develops secondary hyperparathyroidism. What is the typical microscopic change in the parathyroid glands?
Recorded recall sessions: January 2019
A. Solitary parathyroid adenoma
B. Parathyroid carcinoma
C. Squamous metaplasia
D. Diffuse or nodular chief-cell hyperplasia
Answer and explanation
D. Diffuse or nodular chief-cell hyperplasia
Chronic renal impairment leads to phosphate retention, altered vitamin-D activation and disordered calcium homeostasis, chronically stimulating parathyroid-hormone secretion. Prolonged stimulation leads to multiglandular hyperplasia.
A. Typical of many cases of primary hyperparathyroidism rather than chronic secondary stimulation.
B. An uncommon malignant cause of marked primary hyperparathyroidism, not the usual response to renal failure.
C. Does not describe the usual renal-related increase in parathyroid cellular mass.
- Secondary hyperparathyroidism often involves all four glands
- Tertiary hyperparathyroidism is autonomous PTH secretion after longstanding secondary disease
- Monitor calcium, phosphate and PTH in CKD mineral-bone disease
Exam pearl: Renal secondary hyperparathyroidism causes multiglandular parathyroid hyperplasia.
Examiner trap: A single adenoma implies a different pathophysiology from the classic renal secondary process.
Viva extension: What is tertiary hyperparathyroidism? Autonomous PTH production following chronic hyperplasia.
Q119. A middle-aged man has recurrent calcium renal stones, hypercalcaemia and an inappropriately raised PTH with preserved renal function. What is the commonest underlying lesion?
Recorded recall sessions: January 2017; September 2022; September 2024
A. Diffuse secondary parathyroid hyperplasia due to kidney failure
B. Solitary parathyroid adenoma
C. Parathyroid carcinoma
D. Vitamin D intoxication
Answer and explanation
B. Solitary parathyroid adenoma
Autonomous secretion from a single benign parathyroid adenoma accounts for most primary hyperparathyroidism. Increased PTH raises serum calcium through bone resorption, renal calcium handling and vitamin-D activation, predisposing to nephrolithiasis.
A. Secondary hyperparathyroidism is more often associated with chronic kidney disease and normal or low calcium.
C. Can cause severe PTH-dependent hypercalcaemia but accounts for a very small minority of cases.
D. Can produce hypercalcaemia, but feedback normally suppresses PTH rather than elevating it.
- Check paired albumin-adjusted calcium and PTH, renal function, vitamin D and urinary calcium when appropriate.
- Familial hypocalciuric hypercalcaemia is an important biochemical differential.
- Localisation imaging is for operative planning, not for establishing a biochemical diagnosis.
Exam pearl: High calcium with non-suppressed PTH = PTH-dependent hypercalcaemia; most often adenoma.
Examiner trap: A normal or high PTH during true hypercalcaemia is inappropriately non-suppressed.
Viva extension: What test helps distinguish FHH? Urinary calcium excretion or calcium-to-creatinine clearance ratio.
Q185. A 36-year-old woman has erythema nodosum, bilateral hilar lymphadenopathy, serum calcium 2.95 mmol/L and suppressed PTH. Which underlying condition best explains the findings?
Recorded recall sessions: January 2019
A. Primary hyperparathyroidism
B. Secondary hyperparathyroidism
C. Familial hypocalciuric hypercalcaemia
D. Sarcoidosis
Answer and explanation
D. Sarcoidosis
Sarcoid granuloma macrophages express extrarenal 1α-hydroxylase, increasing active vitamin D and intestinal calcium absorption. The resultant hypercalcaemia appropriately suppresses circulating PTH.
A. Primary hyperparathyroidism generally produces inappropriately normal or elevated PTH in hypercalcaemia.
B. Secondary hyperparathyroidism usually produces elevated PTH due to calcium/vitamin D or renal disturbances.
C. Familial hypocalciuric hypercalcaemia may have mild lifelong hypercalcaemia but does not explain erythema nodosum and hilar adenopathy.
- Sarcoidosis may present with Löfgren syndrome: erythema nodosum, bilateral hilar lymphadenopathy and arthritis.
- Activated macrophages generate 1,25-dihydroxyvitamin D independent of renal regulation.
- Measure PTH first when evaluating unexplained hypercalcaemia.
Exam pearl: Hypercalcaemia + suppressed PTH + hilar adenopathy suggests granulomatous vitamin-D activation.
Examiner trap: Normal or low PTH distinguishes this from PTH-driven hypercalcaemia.
Viva extension: What vitamin D metabolite is often increased? 1,25-dihydroxyvitamin D (calcitriol).
Q230. A woman previously treated for a pancreatic neuroendocrine tumour develops primary hyperparathyroidism. Which additional endocrine organ requires directed assessment for a classical MEN1-associated tumour?
Recorded recall sessions: April 2017; September 2020
A. Thyroid parafollicular C cells
B. Adrenal medulla
C. Ovarian granulosa cells
D. Anterior pituitary gland
Answer and explanation
D. Anterior pituitary gland
MEN1 is an autosomal dominant syndrome due to pathogenic MEN1 variants. The characteristic organ triad is parathyroid, duodenopancreatic neuroendocrine system and anterior pituitary; pituitary lesions are often prolactinomas.
A. Medullary thyroid carcinoma is characteristic of MEN2 rather than the classical MEN1 triad.
B. Phaeochromocytoma is a prominent MEN2 association; it is not the third classical MEN1 component.
C. Ovarian granulosa-cell tumours are not one of the three defining MEN1 organ groups.
- MEN1 commonly presents with multigland primary hyperparathyroidism.
- Duodenopancreatic tumours include gastrinoma and insulinoma.
- Pituitary lesions include prolactinomas and other functional/nonfunctional adenomas.
- Family genetic counselling and longitudinal surveillance are important.
Exam pearl: MEN1 = three Ps: parathyroid, pancreatic/duodenal NETs and pituitary.
Examiner trap: MEN2 involves medullary thyroid cancer and phaeochromocytoma; do not mix MEN1 and MEN2.
Viva extension: Which gene causes MEN1? MEN1 on chromosome 11q13, encoding menin.
Q328. A kidney-transplant recipient with longstanding secondary hyperparathyroidism develops persistent hypercalcaemia, low phosphate, raised alkaline phosphatase, elevated PTH and fragility fractures despite good graft function. Which diagnosis is most likely?
Recorded recall sessions: January 2018; January 2019; January 2021; April 2021; May 2022; January 2023; May 2023; January 2024; April 2026
A. Vitamin D deficiency with secondary hyperparathyroidism
B. Tertiary hyperparathyroidism
C. Hypoparathyroidism
D. PTH-independent malignant hypercalcaemia
Answer and explanation
B. Tertiary hyperparathyroidism
Longstanding renal secondary hyperparathyroidism can progress to autonomous multiglandular PTH secretion. After transplantation, improved renal function does not necessarily suppress the hyperplastic glands, producing high calcium and inappropriately elevated PTH, often with phosphate wasting and bone disease. Management depends on severity and persistence and may include calcimimetic therapy or parathyroidectomy.
A. Vitamin D deficiency commonly produces normal or low calcium, rather than persistent PTH-mediated hypercalcaemia after transplantation.
C. Hypoparathyroidism produces low PTH and typically hypocalcaemia, the opposite biochemical pattern.
D. Malignant hypercalcaemia generally suppresses native PTH and requires a different work-up.
- Secondary renal hyperparathyroidism usually causes low or normal calcium with high phosphate before dialysis-related treatment effects.
- Tertiary hyperparathyroidism implies autonomous secretion after prolonged secondary disease.
- Check intact PTH alongside albumin-adjusted or ionised calcium.
- Bone pain, fractures and persistent hypercalcaemia may indicate clinically important disease.
Exam pearl: After kidney transplant, high calcium + high PTH suggests tertiary hyperparathyroidism.
Examiner trap: High calcium alone does not distinguish primary from tertiary disease; renal history and prolonged secondary hyperparathyroidism matter.
Viva extension: What gland pathology is typical? Multiglandular hyperplasia with autonomous nodular change.
Q431. During parathyroid surgery, a surgeon requests rapid intraoperative tissue identification. Which method best describes preparation of a frozen section?
Recorded recall sessions: September 2017; September 2019; April 2021
A. Formalin fixation followed by paraffin embedding
B. Direct immunofluorescence alone
C. Rapid freezing, cryostat sectioning and staining of fresh tissue
D. Leaving the specimen in formalin before cryostat processing
Answer and explanation
C. Rapid freezing, cryostat sectioning and staining of fresh tissue
Fresh tissue is rapidly frozen, cut into thin sections in a cryostat and stained for immediate microscopic assessment, avoiding the time required for routine fixation and paraffin processing.
A. This is standard permanent histology and takes much longer than an intraoperative frozen section.
B. Immunofluorescence is a separate technique and not the routine frozen-section workflow.
D. Formalin fixation defeats the purpose of rapid fresh-tissue frozen section preparation.
- Frozen sections provide rapid but sometimes limited tissue interpretation.
- Paraffin sections usually have superior morphology.
- The surgeon must communicate the precise intraoperative question to pathology.
- Intraoperative PTH measurement may be more useful than frozen section for confirming biochemical cure.
Exam pearl: Frozen section = fresh tissue + cryostat + rapid stain.
Examiner trap: Do not confuse rapid frozen histology with formalin-fixed paraffin sections.
Viva extension: What is a limitation? Freezing artefact may reduce morphological detail and diagnostic certainty.
Q454. A kidney-transplant recipient has persistent tertiary hyperparathyroidism. Which physiological action of parathyroid hormone increases intestinal calcium absorption indirectly?
Recorded recall sessions: April 2025
A. Directly opening intestinal calcium channels independent of vitamin D
B. Increasing renal phosphate reabsorption
C. Stimulating renal 1-alpha-hydroxylase to form calcitriol
D. Reducing distal tubular calcium reabsorption
Answer and explanation
C. Stimulating renal 1-alpha-hydroxylase to form calcitriol
PTH upregulates renal proximal-tubule 1-alpha-hydroxylase, converting 25-hydroxyvitamin D into active 1,25-dihydroxyvitamin D (calcitriol). Calcitriol then increases intestinal calcium and phosphate absorption.
A. The main intestinal effect of PTH is indirect, mediated by calcitriol.
B. PTH decreases proximal tubular phosphate reabsorption, causing phosphaturia.
D. PTH increases renal calcium reabsorption, particularly distally.
- PTH raises serum calcium and tends to lower serum phosphate.
- PTH stimulates osteoblast-lineage cells to express RANKL, increasing osteoclast activity.
- PTH increases distal nephron calcium reabsorption.
- Renal failure impairs calcitriol production and contributes to secondary hyperparathyroidism.
Exam pearl: PTH increases calcitriol synthesis and causes phosphaturia.
Examiner trap: Do not attribute a direct gut action to PTH; vitamin D mediates it.
Viva extension: Why does chronic kidney disease cause secondary hyperparathyroidism? Phosphate retention, reduced calcitriol and hypocalcaemic drive.
Q627. A patient has biochemically confirmed primary hyperparathyroidism with hypercalcaemia and recurrent renal calculi. Neck ultrasound is inconclusive, and localisation would assist planned surgery. Which nuclear medicine study may help localise a solitary adenoma?
Recorded recall sessions: April 2018; May 2022; January 2023; May 2023
A. Radioiodine whole-body scan
B. Bone-density DEXA scan
C. MRI brain with contrast
D. Technetium-99m sestamibi parathyroid scan
Answer and explanation
D. Technetium-99m sestamibi parathyroid scan
Technetium-99m sestamibi scintigraphy is an established method of parathyroid adenoma localisation. It is a preoperative localisation tool, not the diagnostic test for primary hyperparathyroidism; ultrasound is commonly the first imaging modality.
A. Radioiodine evaluates functioning thyroid tissue, not parathyroid adenoma localisation.
B. DEXA assesses osteoporosis but cannot localise an adenoma.
C. Brain MRI does not localise neck parathyroid disease.
- Diagnose primary hyperparathyroidism biochemically with calcium and PTH.
- Preoperative imaging is used only when it can help surgical planning.
- Neck ultrasound is commonly the initial localisation study.
- Sestamibi or other second-line localisation can be used when useful; negative imaging does not exclude disease.
Exam pearl: Sestamibi localises an adenoma; serum calcium/PTH establishes the diagnosis.
Examiner trap: Do not present sestamibi as the first diagnostic test for hypercalcaemia.
Viva extension: Can a patient have primary hyperparathyroidism despite negative imaging? Yes. Imaging can miss small or multigland disease; expert bilateral exploration may still be appropriate.
Q673. A 24-year-old woman previously treated for primary hyperparathyroidism now develops recurrent refractory peptic ulcers and watery diarrhoea. Which hormone is the likely driver of her gastrointestinal symptoms?
Recorded recall sessions: April 2021; January 2025
A. Gastrin
B. Calcitonin
C. Glucagon
D. Secretin
Answer and explanation
A. Gastrin
Primary hyperparathyroidism plus gastrinoma suggests MEN1. Gastrin excess stimulates gastric acid secretion, causing recurrent ulcers and sometimes diarrhoea due to acid-mediated inactivation of pancreatic enzymes and mucosal injury.
B. Calcitonin may cause diarrhoea in medullary thyroid carcinoma but does not explain the classic MEN1 ulcer syndrome.
C. Glucagonoma classically causes diabetes, weight loss and necrolytic migratory erythema.
D. Secretin is used in selected provocative testing for gastrinoma, not as the pathological hormone driving this syndrome.
- MEN1: parathyroid, pancreatic/duodenal neuroendocrine and pituitary tumours.
- Gastrinoma causes Zollinger–Ellison syndrome.
- Gastrin stimulates parietal-cell acid secretion indirectly via ECL histamine.
- Refractory or multiple ulcers warrant consideration of gastrinoma.
Exam pearl: Parathyroid disease plus refractory ulcers and diarrhoea suggests MEN1 gastrinoma.
Examiner trap: Do not confuse gastrinoma-associated diarrhoea with medullary thyroid carcinoma calcitonin diarrhoea.
Viva extension: How is gastrinoma investigated? Fasting gastrin interpreted with gastric pH and medication effects, with specialist-directed additional testing.
Q710. A 40-year-old woman has nausea, constipation and lethargy. She takes large amounts of calcium-carbonate antacid for reflux. Corrected calcium is 3.1 mmol/L, bicarbonate 34 mmol/L, creatinine is increased and PTH is suppressed. What is the most likely diagnosis?
Recorded recall sessions: April 2017; September 2020
A. Calcium-alkali (milk-alkali) syndrome
B. Primary hyperparathyroidism
C. Tertiary hyperparathyroidism
D. Sarcoidosis-related hypercalcaemia
Answer and explanation
A. Calcium-alkali (milk-alkali) syndrome
Calcium-alkali syndrome is caused by excess calcium with absorbable alkali, often from calcium-carbonate antacids or supplements. Its characteristic triad is hypercalcaemia, metabolic alkalosis and renal dysfunction with appropriate suppression of PTH. Stop the source and correct volume depletion while monitoring renal function and electrolytes.
B. PTH is typically elevated or inappropriately normal in primary hyperparathyroidism despite hypercalcaemia.
C. Tertiary hyperparathyroidism generally follows long-standing renal secondary hyperparathyroidism and produces autonomous high PTH.
D. Sarcoidosis can raise calcium through increased extrarenal calcitriol production but does not characteristically produce the calcium-alkali triad after antacid use.
- The triad is hypercalcaemia, metabolic alkalosis and acute or chronic renal impairment.
- PTH is usually suppressed because hypercalcaemia is PTH-independent.
- Calcium carbonate is a common source; thiazides and dehydration may increase risk.
- Initial management includes stopping calcium/alkali and isotonic fluid repletion where clinically appropriate.
Exam pearl: Hypercalcaemia + alkalosis + AKI in an antacid user = calcium-alkali syndrome.
Examiner trap: An isolated low TSH in a recall does not diagnose the cause of hypercalcaemia; biochemical calcium/PTH physiology and the antacid history are decisive.
Viva extension: How does hypercalcaemia worsen renal function? It causes renal vasoconstriction and impaired urinary concentrating ability, promoting volume depletion and reduced GFR.
Q765. A 57-year-old with CKD stage G5 not yet on dialysis has bone pain. Serial blood tests show phosphate 1.9 mmol/L (raised), adjusted calcium 2.05 mmol/L (low), markedly elevated PTH and reduced calcitriol. Which diagnosis best explains the biochemical pattern?
Recorded recall sessions: 2021 (session not specified); May 2022
A. Primary hyperparathyroidism from a solitary adenoma
B. PTH-independent hypercalcaemia of malignancy
C. Tertiary autonomous hyperparathyroidism after a successful transplant
D. Secondary hyperparathyroidism due to CKD-related phosphate retention and reduced calcitriol
Answer and explanation
D. Secondary hyperparathyroidism due to CKD-related phosphate retention and reduced calcitriol
Reduced phosphate excretion and reduced renal 1-alpha hydroxylation of vitamin D contribute to phosphate retention, lower calcium availability and compensatory PTH elevation. In CKD-MBD, PTH, calcium and phosphate must be interpreted as serial trends rather than a single threshold.
A. Primary hyperparathyroidism typically causes hypercalcaemia with low phosphate when renal function permits.
B. PTH is usually suppressed in PTH-independent hypercalcaemia; the vignette has low calcium and high PTH.
C. Tertiary hyperparathyroidism involves autonomous PTH secretion and commonly hypercalcaemia, often after longstanding secondary disease.
- CKD secondary hyperparathyroidism: PTH high, phosphate often high in advanced CKD, calcium low or normal.
- Tertiary hyperparathyroidism typically causes persistent PTH elevation with hypercalcaemia.
- KDIGO advises evaluating trends in calcium, phosphate and PTH together.
- Correct modifiable factors such as high phosphate intake, vitamin D deficiency and hypocalcaemia according to CKD stage.
Exam pearl: High PTH + high phosphate + low/normal calcium in advanced CKD suggests secondary hyperparathyroidism.
Examiner trap: Do not confuse secondary CKD hyperparathyroidism with tertiary disease, where autonomous secretion often produces hypercalcaemia.
Viva extension: Why does phosphate rise in advanced CKD? Loss of renal phosphate clearance; impaired calcitriol production and calcium balance then stimulate PTH.
Q847. A patient with primary hyperparathyroidism has hypercalcaemia and a low serum phosphate concentration. Which direct renal tubular action of parathyroid hormone best explains the phosphate finding?
Recorded recall sessions: May 2022
A. Internalisation of proximal-tubular sodium–phosphate cotransporters, increasing phosphate excretion
B. Increased proximal-tubular phosphate reabsorption
C. Inhibition of renal 1-alpha-hydroxylase
D. Reduced distal-nephron calcium reabsorption
Answer and explanation
A. Internalisation of proximal-tubular sodium–phosphate cotransporters, increasing phosphate excretion
PTH reduces phosphate reabsorption in the proximal tubule by downregulating apical sodium–phosphate cotransporters (including NaPi-IIa and NaPi-IIc). This causes phosphaturia and commonly lowers serum phosphate. Simultaneously PTH increases distal calcium reabsorption and stimulates renal calcitriol formation.
B. This would retain phosphate and is the opposite of PTH’s direct phosphaturic action.
C. PTH stimulates, rather than inhibits, renal 1-alpha-hydroxylase.
D. PTH enhances calcium reabsorption in the distal nephron.
- PTH raises serum calcium but increases urinary phosphate excretion.
- The proximal tubule is the main site of regulated phosphate reabsorption.
- PTH promotes calcitriol synthesis indirectly increasing intestinal calcium absorption.
- Phosphate may be normal in hyperparathyroidism when renal function or other factors modify the response.
Exam pearl: PTH: calcium up, phosphate down—because the proximal tubule wastes phosphate.
Examiner trap: The original options mixed direct and indirect PTH effects. This question isolates the renal phosphate mechanism, distinct from the bank’s existing vitamin-D activation question.
Viva extension: What happens to renal 1-alpha-hydroxylase? PTH stimulates it, increasing calcitriol production.
Q909. A man with long-standing dialysis-dependent CKD has progressively enlarging parathyroid glands, PTH 1600 ng/L, phosphate 2.2 mmol/L and now persistent adjusted calcium 2.95 mmol/L despite control of vitamin-D therapy. Which diagnosis best explains the combination?
Recorded recall sessions: January 2020; January 2021; September 2021; 2021 (session not specified)
A. Primary hypoparathyroidism
B. Isolated vitamin-D deficiency
C. Tertiary hyperparathyroidism with autonomous PTH secretion
D. Familial hypocalciuric hypercalcaemia
Answer and explanation
C. Tertiary hyperparathyroidism with autonomous PTH secretion
After prolonged secondary hyperparathyroidism in advanced CKD, parathyroid hyperplasia can become autonomous, producing tertiary hyperparathyroidism with markedly elevated PTH and hypercalcaemia. Phosphate can remain elevated in dialysis-dependent patients because impaired renal excretion persists despite PTH action.
A. Hypoparathyroidism causes low PTH and typically hypocalcaemia.
B. Vitamin-D deficiency generally causes low or normal calcium with secondary PTH elevation, not autonomous marked hypercalcaemia.
D. FHH typically causes lifelong mild hypercalcaemia with relative hypocalciuria, not severe dialysis-associated hyperparathyroidism.
- Secondary CKD hyperparathyroidism commonly has low/normal calcium, high phosphate and high PTH.
- Tertiary hyperparathyroidism implies autonomous PTH secretion after prolonged stimulation.
- Phosphate may remain high in advanced renal failure even when PTH is very high.
- Treatment is specialist-led and may involve calcimimetics or parathyroidectomy in refractory cases.
Exam pearl: Long-standing CKD + very high PTH + new persistent hypercalcaemia = consider tertiary hyperparathyroidism.
Examiner trap: Do not assume tertiary hyperparathyroidism always causes low phosphate; phosphate retention may persist in dialysis.
Viva extension: Viva: What distinguishes tertiary from secondary hyperparathyroidism? Tertiary disease has autonomous gland function and hypercalcaemia after chronic secondary stimulation.
Q947. A 29-year-old woman has recurrent renal stones from primary hyperparathyroidism. Her father had a prolactinoma, and her brother was treated for a gastrinoma. Which combination most strongly supports multiple endocrine neoplasia type 1 (MEN1)?
Recorded recall sessions: April 2026
A. Medullary thyroid carcinoma, phaeochromocytoma and mucosal neuromas
B. Phaeochromocytoma, medullary thyroid carcinoma and parathyroid hyperplasia
C. Parathyroid neoplasia, pancreatic or duodenal neuroendocrine tumours and pituitary adenomas
D. Papillary thyroid carcinoma, adrenal cortical carcinoma and renal cell carcinoma
Answer and explanation
C. Parathyroid neoplasia, pancreatic or duodenal neuroendocrine tumours and pituitary adenomas
MEN1 (Wermer syndrome) is an autosomal-dominant MEN1/menin tumour-suppressor disorder classically affecting the parathyroids, gastroenteropancreatic neuroendocrine system and anterior pituitary. Familial primary hyperparathyroidism plus prolactinoma or gastrinoma warrants genetic evaluation and structured screening.
A. This constellation suggests MEN2B rather than MEN1.
B. Medullary thyroid carcinoma and phaeochromocytoma point toward MEN2A, not MEN1.
D. This is not the characteristic MEN1 triad.
- The classic three Ps are parathyroid, pancreatic/duodenal NET and pituitary.
- Primary hyperparathyroidism is commonly the earliest and most frequent manifestation.
- MEN1 is inherited in an autosomal-dominant manner and involves the menin protein.
- MEN2 syndromes are RET-related and strongly associated with medullary thyroid carcinoma.
Exam pearl: MEN1 = parathyroid + pancreatic/duodenal NET + pituitary; MEN2 = medullary thyroid carcinoma + phaeochromocytoma.
Examiner trap: The original recall listed no characteristic MEN1 tumour among its options; do not accept its source choices as a valid SBA.
Viva extension: Which gene is mutated in MEN1, and which is associated with MEN2? MEN1 on chromosome 11 encodes menin; RET proto-oncogene variants cause MEN2.
Q1000. A 37-year-old woman has recurrent calcium renal stones, constipation, low mood and a serum-adjusted calcium of 2.95 mmol/L. PTH is 11 pmol/L (reference 1.6–6.9). Which diagnosis best explains the combination?
Recorded recall sessions: January 2020
A. Primary hyperparathyroidism
B. Secondary hyperparathyroidism due to chronic kidney disease
C. Thyrotoxicosis
D. Familial hypocalciuric hypercalcaemia
Answer and explanation
A. Primary hyperparathyroidism
Hypercalcaemia with an inappropriately raised PTH indicates PTH-dependent hypercalcaemia. Primary hyperparathyroidism can produce renal calculi, gastrointestinal symptoms and neuropsychiatric features. Confirm the biochemical pattern, assess renal function, vitamin D and urinary calcium, and consider definitive parathyroidectomy according to indications.
B. Usually occurs with chronic kidney disease, often with normal or low calcium rather than this classic hypercalcaemic presentation.
C. Can cause hypercalcaemia, but PTH would ordinarily be suppressed.
D. Causes lifelong mild PTH-dependent hypercalcaemia with typically low urine calcium; distinguish with calcium/creatinine clearance ratio and family history.
- Measure serum calcium and PTH together rather than interpreting either alone.
- Check 25-hydroxyvitamin D, creatinine/eGFR and urinary calcium.
- Renal stones are a clinically important indication to consider parathyroidectomy.
- Do not rely on parathyroid imaging to establish the biochemical diagnosis.
Exam pearl: Stones + hypercalcaemia + nonsuppressed PTH strongly suggest primary hyperparathyroidism.
Examiner trap: Psychiatric symptoms alone are nonspecific; confirm the PTH-dependent biochemical pattern.
Viva extension: How is familial hypocalciuric hypercalcaemia distinguished? Low urinary calcium excretion, family history and, where needed, genetic assessment; overlap exists.
Q587. A thyroidectomised patient takes liothyronine (T3) alone. Blood is sampled near the post-dose peak. Which biochemical pattern is most consistent with substantial exogenous T3 exposure?
Recorded recall sessions: January 2021
A. High TSH, low T3, high free T4
B. Suppressed TSH, elevated T3, relatively low free T4
C. High calcitonin with normal T3
D. High TSH and high free T4
Answer and explanation
B. Suppressed TSH, elevated T3, relatively low free T4
Exogenous T3 suppresses pituitary TSH by negative feedback. With T3-only therapy, free T4 can be low because little or no T4 is administered. Serum T3 varies markedly with dose timing. Routine differentiated thyroid cancer replacement is generally levothyroxine-based rather than long-term T3 monotherapy.
A. High TSH with low T3 implies inadequate replacement rather than substantial T3 exposure.
C. Calcitonin is a C-cell marker and not the typical response to liothyronine.
D. High TSH despite high free T4 suggests a different problem such as assay interference or rare central disorders.
- T3 has a shorter half-life than T4.
- Liothyronine can cause post-dose T3 peaks.
- Thyroglobulin, not calcitonin, is used for follow-up of differentiated thyroid carcinoma.
- TSH suppression targets are individualised to recurrence risk and response.
Exam pearl: Exogenous T3: TSH down, T3 up, T4 often low on T3-only treatment.
Examiner trap: Do not assume T3-only therapy is standard long-term management after thyroid cancer.
Viva extension: What is the standard replacement drug after differentiated thyroidectomy? Levothyroxine, with risk-adapted TSH targets.
Q40. A day after total thyroidectomy, a patient develops perioral tingling, carpopedal spasm and muscle twitching. Which complication is most likely?
Recorded recall sessions: September 2019
A. Hypercalcaemia
B. Hypernatraemia
C. Hypocalcaemia due to transient hypoparathyroidism
D. Isolated hyperkalaemia
Answer and explanation
C. Hypocalcaemia due to transient hypoparathyroidism
Unintentional removal, bruising or devascularisation of parathyroids during thyroidectomy may impair PTH secretion, lowering ionised calcium. Tetany and paraesthesiae require prompt assessment of calcium, magnesium and ECG.
A. Usually causes constipation, renal stones, thirst and neurocognitive change rather than acute tetany.
B. Can cause neurological dysfunction but not the classic post-thyroidectomy tetany pattern.
D. Primarily threatens cardiac conduction and does not cause typical tetany.
- Chvostek and Trousseau signs may be present
- QT may be prolonged
- Severe symptomatic hypocalcaemia may require IV calcium under monitoring.
Exam pearl: Post-thyroidectomy tingling and tetany = check calcium.
Examiner trap: A rapidly expanding neck haematoma is another immediate threat but presents mainly with airway compromise.
Viva extension: How does PTH regulate calcium? Increases renal calcium reabsorption and stimulates calcitriol production.
Q85. A woman becomes irritable and develops carpopedal twitching within 24 hours of total thyroidectomy. Which electrolyte disturbance is most likely?
Recorded recall sessions: September 2020
A. Hypocalcaemia
B. Hypercalcaemia
C. Hypernatraemia
D. Hypokalaemia
Answer and explanation
A. Hypocalcaemia
Transient parathyroid devascularisation or inadvertent removal during thyroidectomy can lower PTH, reduce ionised calcium and cause neuromuscular hyperexcitability. Check ionised or corrected serum calcium, magnesium and PTH when clinically appropriate.
B. Typically causes polyuria, constipation and reduced neuromuscular excitability rather than acute tetany.
C. Can affect consciousness but does not characteristically cause postoperative tetany.
D. May cause muscle weakness or arrhythmia but is not the classic complication due to parathyroid injury.
- Look for perioral tingling, Chvostek and Trousseau signs
- Severe symptomatic hypocalcaemia may require intravenous calcium
- Also monitor voice changes and airway-threatening neck haematoma after thyroidectomy
Exam pearl: Post-thyroidectomy tetany is hypocalcaemia until proved otherwise.
Examiner trap: Distinguish hypocalcaemic tetany from recurrent-laryngeal-nerve injury causing dysphonia.
Viva extension: What is the role of the parathyroid glands? PTH regulates extracellular calcium balance.
Q144. A 52-year-old woman reports fatigue and has a small goitre. TSH is 12 mIU/L (0.4–4.3) and free T4 is 10 pmol/L (laboratory reference 9–26). How should this biochemical pattern be classified?
Recorded recall sessions: September 2019; September 2020; September 2021; 2021 (session not specified)
A. Overt primary hyperthyroidism
B. Secondary hypothyroidism
C. Overt primary hypothyroidism
D. Subclinical primary hypothyroidism
Answer and explanation
D. Subclinical primary hypothyroidism
An elevated TSH with free T4 still within the laboratory reference range defines subclinical primary hypothyroidism. TSH should be repeated and anti-TPO antibodies considered; persistent TSH ≥10 mIU/L can justify considering levothyroxine.
A. Hyperthyroidism would ordinarily suppress TSH and increase FT4 and/or FT3.
B. Central hypothyroidism usually has a low FT4 with inappropriately low or normal TSH rather than TSH 12.
C. Overt hypothyroidism requires free T4 below the reference interval; here it is low-normal.
- Subclinical = high TSH, normal FT4.
- Overt primary = high TSH, low FT4.
- Repeat TSH and FT4 to confirm persistence.
- NICE considers treatment when TSH ≥10 on two tests three months apart.
Exam pearl: High TSH with normal FT4 = subclinical hypothyroidism.
Examiner trap: A free T4 at the lower limit of normal is still normal by the stated laboratory range.
Viva extension: When does NICE suggest considering levothyroxine? Persistent TSH ≥10 mIU/L on two occasions three months apart.
Q154. A thyroid aspirate shows large oncocytic follicular cells with abundant granular eosinophilic cytoplasm and prominent nuclei. In which chronic inflammatory thyroid disorder are such Hürthle cells classically prominent?
Recorded recall sessions: September 2018; January 2020; May 2022
A. Hashimoto thyroiditis
B. Graves disease
C. Medullary thyroid carcinoma
D. Anaplastic thyroid carcinoma
Answer and explanation
A. Hashimoto thyroiditis
Hürthle cells are oncocytic follicular epithelial cells rich in mitochondria. They occur in Hashimoto thyroiditis, although they are not specific and also occur in Hürthle-cell neoplasms.
B. Graves is associated with hyperplastic follicular epithelium and scalloped colloid, not the classic lymphocytic thyroiditis with Hürthle metaplasia.
C. Medullary carcinoma derives from C cells and often shows amyloid stroma, not benign Hürthle metaplasia.
D. Anaplastic carcinoma shows marked pleomorphism and aggressive undifferentiated cells rather than characteristic benign oncocytic change.
- Hashimoto thyroiditis often has lymphocytic infiltrates and germinal centres.
- Hürthle cells have abundant granular eosinophilic cytoplasm.
- Oncocytic cells alone cannot establish benign versus malignant neoplasm.
- Clinical, cytological and imaging context is necessary.
Exam pearl: Hürthle cells + lymphocytes = consider Hashimoto thyroiditis.
Examiner trap: Hürthle cells are not pathognomonic for Hashimoto; oncocytic tumours exist.
Viva extension: Why is the cytoplasm granular? Abundant mitochondria.
Q178. An eight-week-pregnant woman has confirmed symptomatic Graves hyperthyroidism requiring antithyroid medication. Which drug is generally preferred during the first trimester?
Recorded recall sessions: September 2019
A. Propylthiouracil (PTU)
B. Carbimazole
C. Radioactive iodine
D. Levothyroxine
Answer and explanation
A. Propylthiouracil (PTU)
When antithyroid treatment is needed in the first trimester, PTU is generally preferred because methimazole/carbimazole exposure is associated with rare but important embryopathy. PTU carries a hepatotoxicity risk, so clinicians reassess therapy after the first trimester and aim for the lowest effective dose.
B. Carbimazole is converted to methimazole, which is associated with a characteristic embryopathy when used early in pregnancy.
C. Radioiodine is contraindicated in pregnancy because fetal thyroid tissue can be damaged.
D. Thyroxine replacement would worsen untreated hyperthyroidism rather than inhibit hormone synthesis.
- Confirm true overt hyperthyroidism; transient gestational thyrotoxicosis may need no antithyroid drug.
- Use the minimum effective dose and monitor thyroid function frequently.
- PTU hepatotoxicity is a key reason to consider switching after the first trimester.
- Radioiodine is contraindicated throughout pregnancy.
Exam pearl: First trimester Graves needing medication = PTU.
Examiner trap: The correct drug depends on gestational age and whether medication is actually required.
Viva extension: Why is carbimazole avoided in early pregnancy? Risk of methimazole/carbimazole embryopathy.
Q179. Three months after thyroidectomy, a teacher cannot project her voice or produce high-pitched notes, although her everyday speaking voice is largely preserved. Which nerve was most likely injured?
Recorded recall sessions: September 2020; September 2022; May 2023; September 2024
A. Recurrent laryngeal nerve
B. External branch of the superior laryngeal nerve
C. Hypoglossal nerve
D. Phrenic nerve
Answer and explanation
B. External branch of the superior laryngeal nerve
The external branch of the superior laryngeal nerve innervates the cricothyroid muscle, which tenses and lengthens the vocal folds to increase pitch. Injury can impair high notes and vocal projection, especially noticeable in singers and teachers.
A. Unilateral RLN injury more typically causes breathy hoarseness from vocal-fold paresis; bilateral injury may compromise the airway.
C. CN XII injury affects tongue movement and articulation rather than selective pitch control.
D. This nerve supplies the diaphragm and does not innervate the laryngeal pitch-adjusting muscle.
- The external superior laryngeal nerve runs near the superior thyroid vascular pedicle.
- Cricothyroid is the key pitch-tensing muscle.
- Most other intrinsic laryngeal muscles receive recurrent laryngeal innervation.
- The internal superior laryngeal branch provides sensation above the vocal folds.
Exam pearl: Cannot sing high notes after thyroidectomy = external superior laryngeal nerve.
Examiner trap: Voice fatigue and loss of pitch can be subtle despite preserved conversational speech.
Viva extension: Which muscle is denervated? Cricothyroid.
Q229. Two days after total thyroidectomy, a 50-year-old woman develops circumoral tingling, carpopedal spasm and a prolonged QT interval. Which biochemical abnormality is most directly responsible?
Recorded recall sessions: January 2019
A. Hypernatraemia
B. Hyperkalaemia
C. Low ionised serum calcium
D. Isolated hyperchloraemia
Answer and explanation
C. Low ionised serum calcium
Postoperative parathyroid stunning, devascularisation or inadvertent removal can lower PTH and ionised calcium. Hypocalcaemia increases neuromuscular excitability, causing perioral paraesthesia, tetany and QT prolongation.
A. High sodium does not classically cause tetany and QT prolongation after thyroid surgery.
B. High potassium typically causes peaked T waves and conduction abnormalities rather than classic hypocalcaemic tetany.
D. Chloride elevation does not explain the neuromuscular irritability pattern.
- Measure adjusted/ionised calcium and PTH after concerning symptoms.
- Check magnesium because hypomagnesaemia can impair PTH secretion and action.
- Symptomatic severe hypocalcaemia may require monitored intravenous calcium.
- Long-term supplementation depends on parathyroid recovery.
Exam pearl: Post-thyroidectomy tingling + carpopedal spasm = check calcium and PTH urgently.
Examiner trap: Low magnesium can cause refractory hypocalcaemia; do not treat calcium alone without assessing it.
Viva extension: What ECG change is typical of hypocalcaemia? QT interval prolongation.
Q231. A woman has biochemically confirmed primary hyperparathyroidism with recurrent calcium stones. Her surgeon is planning focused parathyroidectomy. Which nuclear medicine investigation can help localise an abnormal parathyroid gland?
Recorded recall sessions: January 2021
A. Technetium-99m sestamibi scintigraphy
B. Serum calcium measurement alone
C. Plain cervical radiography
D. Routine whole-body bone scan
Answer and explanation
A. Technetium-99m sestamibi scintigraphy
Technetium-99m sestamibi imaging, often with SPECT/CT, is a recognised preoperative localisation method, frequently complemented by expert cervical ultrasound. Imaging is performed to guide surgery after biochemical diagnosis, not to diagnose hyperparathyroidism.
B. Calcium helps establish the biochemical diagnosis but cannot anatomically localise a gland.
C. Plain radiographs have poor sensitivity for parathyroid adenomas.
D. Bone scintigraphy evaluates skeletal turnover and does not specifically localise a parathyroid adenoma.
- Confirm primary hyperparathyroidism using calcium and inappropriately raised/non-suppressed PTH.
- Sestamibi can help locate ectopic or enlarged glands.
- Negative localisation imaging does not exclude primary hyperparathyroidism.
- Multigland disease reduces the sensitivity of focused localisation approaches.
Exam pearl: Parathyroid imaging is for localisation, not biochemical diagnosis.
Examiner trap: A negative sestamibi scan does not rule out surgically significant disease.
Viva extension: Name another first-line localisation modality: high-resolution cervical ultrasound.
Q243. A woman with poorly controlled Graves disease becomes febrile, agitated and tachycardic with atrial fibrillation shortly after surgery. Thyroid storm is suspected. Which treatment bundle is appropriate?
Recorded recall sessions: May 2022
A. Critical-care support, beta-blockade if safe, thionamide, then iodine, plus glucocorticoid
B. Urgent thyroidectomy before medical stabilisation
C. Beta-blocker alone
D. Iodine before any thionamide
Answer and explanation
A. Critical-care support, beta-blockade if safe, thionamide, then iodine, plus glucocorticoid
Thyroid storm is a life-threatening clinical syndrome requiring simultaneous supportive care, control of adrenergic manifestations, inhibition of thyroid hormone synthesis, inhibition of hormone release and glucocorticoid treatment. Iodine is conventionally given at least one hour after thionamide.
B. Surgery during uncontrolled storm carries major risk and is not the initial treatment.
C. Rate control does not suppress ongoing thyroid hormone synthesis or release.
D. Iodine is generally administered after thionamide to avoid providing substrate for new hormone synthesis.
- Treat precipitants such as infection or surgery-related stress.
- Esmolol may allow careful titration; beta-blockers can be hazardous in decompensated heart failure.
- PTU also reduces peripheral T4-to-T3 conversion, though methimazole is often used.
- Glucocorticoids reduce peripheral conversion and support possible relative adrenal insufficiency.
Exam pearl: Thyroid storm: beta-blocker + thionamide → iodine + steroid + supportive care.
Examiner trap: Do not give iodine before thionamide; avoid reflex high-dose beta-blockade in unstable heart failure.
Viva extension: Why administer glucocorticoids? They reduce T4-to-T3 conversion and cover relative adrenal insufficiency.
Q254. A 50-year-old woman has fatigue, a firm diffusely enlarged thyroid, TSH 14 mIU/L and low free T4. Which blood test most strongly supports autoimmune Hashimoto thyroiditis as the cause?
Recorded recall sessions: September 2020; April 2021
A. Serum calcitonin
B. TSH-receptor stimulating antibodies
C. Anti-thyroid peroxidase antibodies
D. Plasma metanephrines
Answer and explanation
C. Anti-thyroid peroxidase antibodies
Anti-TPO antibodies are commonly positive in autoimmune chronic lymphocytic thyroiditis and support the aetiology of primary hypothyroidism. TSH and free T4 establish thyroid dysfunction but do not by themselves identify autoimmunity.
A. A marker associated with medullary thyroid carcinoma, not a diagnostic test for Hashimoto disease.
B. More characteristic of Graves hyperthyroidism.
D. Used to investigate catecholamine excess, not autoimmune thyroiditis.
- Hashimoto disease is a common cause of primary hypothyroidism.
- Typical biochemistry is elevated TSH with low free T4 in overt disease.
- Anti-thyroglobulin antibodies may also occur but are less diagnostically useful than anti-TPO.
- Rapid enlargement or compressive symptoms merit evaluation for malignancy including thyroid lymphoma.
Exam pearl: Firm goitre + primary hypothyroidism + anti-TPO positivity = Hashimoto thyroiditis.
Examiner trap: Anti-TPO supports the diagnosis but antibody positivity alone does not establish clinically significant hypothyroidism.
Viva extension: Which histological cells are classically seen? Hürthle (oncocytic) cells with lymphoid follicles.
Q282. A 19-year-old woman reports fatigue, amenorrhoea and cold intolerance. Her free T4 is low and TSH is also low; pituitary MRI identifies a sellar mass. What is the best explanation for this thyroid profile?
Recorded recall sessions: January 2021
A. Central hypothyroidism from pituitary dysfunction
B. Primary Hashimoto thyroiditis
C. Graves disease
D. Isolated thyroid hormone resistance
Answer and explanation
A. Central hypothyroidism from pituitary dysfunction
Low free T4 with a low or inappropriately normal TSH suggests inadequate pituitary or hypothalamic stimulation. A sellar mass and other pituitary symptoms support central hypothyroidism.
B. Primary thyroid failure typically causes a raised TSH because the pituitary responds to low circulating thyroid hormone.
C. Untreated Graves hyperthyroidism generally produces high free T4/T3 with suppressed TSH.
D. Thyroid hormone resistance generally does not produce a straightforward low TSH plus low free T4 pattern in a patient with a sellar mass.
- Check other pituitary axes, particularly adrenal function, before starting levothyroxine.
- TSH alone is unreliable for monitoring central hypothyroidism.
- Free T4 guides replacement dosing in central disease.
- A low TSH does not always mean hyperthyroidism.
Exam pearl: Low free T4 + inappropriately low/normal TSH = central hypothyroidism.
Examiner trap: Starting thyroid hormone before recognising adrenal insufficiency may precipitate adrenal crisis.
Viva extension: Which hormone axis must be assessed urgently? The hypothalamic–pituitary–adrenal axis.
Q287. After thyroidectomy, a patient develops persistent breathy hoarseness and a weak cough. Flexible laryngoscopy demonstrates an immobile unilateral vocal fold. Which nerve was most likely injured?
Recorded recall sessions: September 2020
A. External branch of superior laryngeal nerve
B. Spinal accessory nerve
C. Hypoglossal nerve
D. Recurrent laryngeal nerve
Answer and explanation
D. Recurrent laryngeal nerve
The recurrent laryngeal nerve supplies all intrinsic laryngeal muscles except cricothyroid. Unilateral injury causes vocal-fold paresis or paralysis with dysphonia and potentially aspiration.
A. This innervates cricothyroid and chiefly affects pitch elevation and vocal projection; it does not usually cause a fixed paralysed vocal fold.
B. This supplies sternocleidomastoid and trapezius and produces shoulder weakness, not vocal-fold immobility.
C. This controls tongue movements; palsy causes tongue deviation and dysarthria rather than isolated vocal-fold paralysis.
- The left recurrent laryngeal nerve loops beneath the aortic arch; the right beneath the subclavian artery.
- Bilateral recurrent laryngeal nerve injury may threaten the airway.
- Laryngoscopy confirms vocal-fold movement abnormalities.
- The external superior laryngeal nerve is particularly vulnerable near superior thyroid vessels.
Exam pearl: Post-thyroidectomy breathy hoarseness + immobile cord = recurrent laryngeal nerve.
Examiner trap: Loss of high-pitched phonation points more toward external superior laryngeal nerve injury.
Viva extension: Which intrinsic muscle is not supplied by the recurrent laryngeal nerve? Cricothyroid.
Q352. A patient undergoing parathyroidectomy requires rapid intraoperative confirmation that a small excised specimen is parathyroid tissue. Which laboratory preparation is characteristic of a frozen section?
Recorded recall sessions: April 2021
A. Routine formalin fixation followed by paraffin embedding
B. Decalcification before paraffin embedding
C. Fresh tissue is rapidly frozen in a cryostat, sectioned and stained
D. Direct cytological smear without tissue sectioning
Answer and explanation
C. Fresh tissue is rapidly frozen in a cryostat, sectioned and stained
Fresh tissue is frozen, cut into thin sections in a cryostat, then rapidly stained (commonly H&E) for intraoperative microscopic assessment. Permanent formalin-fixed sections generally offer better morphology but take longer.
A. Formalin-paraffin processing provides permanent sections but is too slow for a typical intraoperative frozen-section consultation.
B. Decalcification is used for mineralised tissue and is not the defining step of frozen-section analysis.
D. Touch-imprint cytology can supplement frozen section but is not itself a cryostat-cut tissue section.
- Cryostat preparation avoids the delay of routine paraffin embedding.
- Frozen-section artefact can reduce morphological detail.
- The pathologist must correlate morphology with operative findings.
- Intraoperative PTH kinetics, when used, assess biochemical response rather than tissue identity.
Exam pearl: Frozen section = fresh frozen tissue + cryostat + rapid staining.
Examiner trap: Do not confuse a frozen section with a touch-imprint smear or routine formalin-fixed H&E.
Viva extension: How can successful excision be assessed biochemically? By an appropriate fall in intraoperative PTH, interpreted according to the local protocol.
Q393. A woman has suppressed TSH, elevated free T3 and a free T4 within the laboratory reference range. Which biochemical pattern does this represent?
Recorded recall sessions: May 2022
A. T3 thyrotoxicosis
B. Primary hypothyroidism
C. Central hypothyroidism
D. Euthyroid sick syndrome
Answer and explanation
A. T3 thyrotoxicosis
T3-predominant thyrotoxicosis is defined by a suppressed TSH with elevated T3 despite normal free T4. It may be an early presentation of Graves disease or autonomous nodular thyroid disease. Clinical evaluation and aetiological tests are required.
B. Primary hypothyroidism generally produces elevated TSH with low free T4.
C. Central hypothyroidism usually shows low free T4 with an inappropriately low or normal TSH.
D. Non-thyroidal illness commonly lowers T3; it does not characteristically produce elevated T3 with suppressed TSH.
- TSH is highly sensitive for primary thyroid dysfunction.
- Check T3 when TSH is suppressed but T4 is normal and thyrotoxicosis is suspected.
- TRAb supports Graves disease when appropriate.
- Biotin supplements can interfere with some immunoassays.
Exam pearl: Low TSH + high T3 + normal T4 = T3 toxicosis.
Examiner trap: Do not call this subclinical hyperthyroidism: T3 is overtly elevated.
Viva extension: What causes T3-predominant hyperthyroidism? Graves disease or toxic nodular autonomy.
Q414. A breastfeeding woman is confirmed to have recurrent Graves hyperthyroidism rather than transient postpartum thyroiditis. She requires a low-dose antithyroid drug. Which treatment is generally compatible with continued breastfeeding under specialist supervision?
Recorded recall sessions: April 2025
A. Radioiodine while continuing breastfeeding
B. No treatment regardless of symptoms or biochemical severity
C. Carbimazole at an appropriate low dose
D. High-dose iodine supplements as sole therapy
Answer and explanation
C. Carbimazole at an appropriate low dose
Carbimazole (converted to methimazole) is generally compatible with breastfeeding at appropriately prescribed doses; maternal thyroid control and infant wellbeing should be monitored. Radioiodine is contraindicated during breastfeeding. Postpartum thyroiditis, by contrast, usually does not respond to thionamides because hormone release rather than synthesis predominates.
A. Radioiodine treatment is incompatible with breastfeeding and requires specific cessation precautions.
B. Persistent Graves thyrotoxicosis may require active therapy to protect maternal health.
D. Iodine supplements are not a safe substitute for evidence-based antithyroid treatment and excess iodine can disrupt thyroid function.
- Carbimazole/methimazole is often preferred during lactation when thionamides are needed.
- Use the lowest effective dose with endocrine follow-up.
- Radioiodine is contraindicated during breastfeeding.
- Distinguish Graves disease from destructive postpartum thyroiditis before prescribing thionamides.
Exam pearl: Graves disease in a breastfeeding mother can usually be treated with low-dose carbimazole.
Examiner trap: Do not give antithyroid drugs for simple postpartum thyroiditis without evidence of increased synthesis.
Viva extension: How distinguish Graves from postpartum thyroiditis? TRAb, clinical features and appropriate imaging/biochemical assessment.
Q489. A 28-year-old non-pregnant woman has biochemically confirmed Graves hyperthyroidism that relapsed after an adequate 18-month course of carbimazole. She has no large goitre or suspicious nodule and prefers definitive non-surgical treatment. Which is the best option?
Recorded recall sessions: 2021 (session not specified)
A. Indefinite high-dose carbimazole without reassessment
B. Levothyroxine alone
C. Radioactive iodine treatment after counselling and appropriate preparation
D. Propylthiouracil solely because relapse occurred
Answer and explanation
C. Radioactive iodine treatment after counselling and appropriate preparation
After relapse following an adequate antithyroid-drug course, radioactive iodine or surgery are recognised definitive options. In a non-pregnant patient who prefers to avoid surgery and has no contraindication, radioiodine is appropriate; future hypothyroidism is expected and monitored.
A. Long-term antithyroid therapy can be an individualised option, but high-dose indefinite treatment is not the chosen definitive approach here.
B. Thyroxine replaces deficient hormone and would worsen untreated hyperthyroidism.
D. Switching thionamides does not provide definitive treatment and PTU has important hepatotoxicity risks.
- Definitive options after relapse are radioiodine or thyroidectomy.
- Radioiodine is contraindicated during pregnancy and breastfeeding.
- Antithyroid therapy and beta-blockade may be needed before definitive treatment.
- Radioiodine can worsen thyroid eye disease; evaluate risk and prophylaxis.
Exam pearl: Relapsed Graves after antithyroid drugs: consider radioiodine or surgery.
Examiner trap: The best option depends on pregnancy plans, orbitopathy, goitre, cancer suspicion and preference.
Viva extension: When is thyroidectomy preferred? Compression, suspected malignancy or unsuitability of radioiodine/medical therapy.
Q571. A 35-year-old woman has diffuse smooth goitre, weight loss, heat intolerance, tremor and suppressed TSH. Thyroid histology demonstrates tall crowded follicular epithelium, papillary infoldings without fibrovascular cores and scalloped colloid. Which diagnosis best fits?
Recorded recall sessions: January 2020
A. Follicular adenoma
B. Hashimoto thyroiditis
C. Graves disease
D. Follicular carcinoma
Answer and explanation
C. Graves disease
Graves hyperthyroidism causes diffuse follicular epithelial hyperplasia, tall columnar cells, infoldings and colloid resorption giving a scalloped appearance. TSH-receptor-stimulating antibodies are the pathophysiological driver.
A. A follicular adenoma is an encapsulated solitary neoplasm rather than diffuse hyperplasia.
B. Hashimoto thyroiditis shows lymphoid follicles with germinal centres, follicular destruction and Hürthle-cell change.
D. Follicular carcinoma requires capsular and/or vascular invasion, which is not a feature of diffuse Graves hyperplasia.
- TSH receptor antibodies stimulate thyroid hormone synthesis.
- Histology can show scalloped colloid and epithelial infoldings.
- Graves ophthalmopathy is an autoimmune extrathyroidal manifestation.
- Biochemical diagnosis is based on suppressed TSH with elevated thyroid hormones, not routine biopsy.
Exam pearl: Scalloped colloid with diffuse follicular hyperplasia is characteristic of Graves disease.
Examiner trap: Papillary infoldings in Graves lack the true fibrovascular cores and nuclear features of papillary carcinoma.
Viva extension: Which autoantibody is central to Graves disease? TSH-receptor-stimulating immunoglobulin.
Q648. A 25-year-old woman has weight loss despite increased appetite, heat intolerance, fine tremor and a diffuse thyroid bruit. Which thyroid-function profile best supports overt primary hyperthyroidism?
Recorded recall sessions: September 2017; April 2021; September 2021; January 2024
A. TSH 0.01 mIU/L, free T4 38 pmol/L, free T3 12 pmol/L
B. TSH 11 mIU/L, free T4 7 pmol/L, free T3 2 pmol/L
C. TSH 2.5 mIU/L, free T4 17 pmol/L, free T3 5 pmol/L
D. TSH 0.02 mIU/L, free T4 17 pmol/L, free T3 5 pmol/L
Answer and explanation
A. TSH 0.01 mIU/L, free T4 38 pmol/L, free T3 12 pmol/L
In overt primary hyperthyroidism, excess circulating thyroid hormone suppresses pituitary TSH through negative feedback. Elevated free T4 and/or T3 with suppressed TSH is the biochemical signature; a diffuse bruit supports hypervascular Graves disease.
B. High TSH with low free T4 is overt primary hypothyroidism, not thyrotoxicosis.
C. All three values are within a typical euthyroid pattern.
D. Suppressed TSH with normal free T4 and T3 suggests subclinical hyperthyroidism rather than overt disease.
- TSH is usually the most sensitive initial test for primary thyroid dysfunction.
- Overt thyrotoxicosis: suppressed TSH and elevated free T4 and/or free T3.
- T3 thyrotoxicosis may have normal free T4 with raised T3.
- TRAb supports Graves disease; thyroiditis usually shows low rather than increased radionuclide uptake.
Exam pearl: Low TSH plus high free T4/T3 = overt primary hyperthyroidism.
Examiner trap: A low TSH with normal free hormones is subclinical hyperthyroidism; do not confuse it with overt disease.
Viva extension: How can Graves disease be distinguished from thyroiditis? TRAb positivity and diffusely increased radionuclide uptake favour Graves; destructive thyroiditis usually has low uptake.
Q658. A young woman with positive anti-thyroid peroxidase antibodies has fatigue, weight gain, constipation and cold intolerance. Which thyroid function profile indicates overt primary hypothyroidism?
Recorded recall sessions: September 2022
A. Elevated TSH with low free T4
B. Low TSH with elevated free T4
C. Low TSH with low free T4
D. Elevated TSH with normal free T4
Answer and explanation
A. Elevated TSH with low free T4
Autoimmune destruction of the thyroid gland reduces free T4 production; reduced negative feedback causes pituitary TSH to rise. The combination of high TSH and low free T4 establishes overt primary hypothyroidism in the appropriate context.
B. Low TSH and high free T4 indicates overt thyrotoxicosis.
C. Low or inappropriately normal TSH with low free T4 suggests central hypothyroidism or non-thyroidal illness rather than primary thyroid failure.
D. High TSH with normal free T4 defines subclinical primary hypothyroidism.
- Hashimoto thyroiditis is a common cause of primary hypothyroidism in iodine-sufficient populations.
- Anti-TPO antibodies support autoimmune thyroiditis but do not by themselves define hormone deficiency.
- Overt primary hypothyroidism: high TSH and low free T4.
- Subclinical primary hypothyroidism: high TSH with normal free T4.
Exam pearl: High TSH + low free T4 = overt primary hypothyroidism.
Examiner trap: Antibody positivity alone does not mean the patient is overtly hypothyroid; use the hormone profile.
Viva extension: What is first-line replacement treatment for overt primary hypothyroidism? Levothyroxine, with dose and monitoring individualised to age, cardiac disease and clinical circumstances.
Q707. Two months after delivery, a breastfeeding woman has palpitations, tremor and a mildly raised free T4 with suppressed TSH. She has no eye signs or thyroid bruit; TSH-receptor antibodies are negative and ultrasound shows no increased thyroid vascularity. She is clinically stable. What is the most appropriate initial drug for symptom control?
Recorded recall sessions: April 2026
A. Carbimazole to suppress hormone synthesis
B. Low-dose propranolol or metoprolol
C. Radioiodine ablation
D. High-dose levothyroxine
Answer and explanation
B. Low-dose propranolol or metoprolol
The early thyrotoxic phase of postpartum thyroiditis results from destructive release of preformed hormone, not increased synthesis. A short course of a compatible beta blocker at the lowest effective dose can control palpitations and tremor. Antithyroid drugs are ineffective for destructive thyroiditis. Thyroid function should be reassessed for a later hypothyroid phase.
A. Carbimazole inhibits new hormone synthesis and is not indicated for destructive postpartum thyroiditis.
C. Radioiodine is inappropriate for transient destructive thyroiditis and contraindicated during breastfeeding.
D. Levothyroxine treats hypothyroidism and would worsen the thyrotoxic phase.
- Postpartum thyroiditis often begins within months after delivery.
- Thyrotoxic, hypothyroid or biphasic courses can occur.
- TRAb positivity and increased thyroid vascularity favour Graves disease over destructive thyroiditis.
- Propranolol or metoprolol can be used for troublesome symptoms when clinically appropriate during lactation.
- Repeat TSH and free T4 to identify recovery or a subsequent hypothyroid phase.
Exam pearl: Destructive postpartum thyrotoxicosis: beta blocker for symptoms; antithyroid drugs do not help.
Examiner trap: Postpartum Graves disease requires different management; distinguish it from thyroiditis rather than treating every low TSH with carbimazole.
Viva extension: Why are thionamides ineffective in postpartum thyroiditis? Excess hormone is released from damaged follicles rather than newly synthesised.
Q783. A 30-year-old woman has taken carbimazole for Graves disease for six weeks. She develops fever, severe sore throat and mouth ulcers. She is haemodynamically stable but looks unwell. Which immediate action is most appropriate?
Recorded recall sessions: 2022/2023 (mixed/uncertain session)
A. Continue carbimazole and review thyroid function in six weeks
B. Increase carbimazole because symptoms indicate persistent thyrotoxicosis
C. Switch directly to propylthiouracil without blood testing
D. Stop carbimazole immediately and obtain an urgent full blood count with differential
Answer and explanation
D. Stop carbimazole immediately and obtain an urgent full blood count with differential
Fever, sore throat and oral ulcers while taking carbimazole can herald severe neutropenia or agranulocytosis. The antithyroid drug should be stopped immediately and an urgent differential white-cell count obtained. If neutropenia or febrile neutropenia is confirmed, urgent hospital management including infection assessment and appropriate antibiotics is required.
A. Continuing a possible causative drug while delaying assessment can permit life-threatening infection.
B. Increasing the drug may worsen a potentially serious adverse effect.
C. Propylthiouracil is not an automatic safe substitute in suspected thionamide agranulocytosis because cross-reactivity can occur.
- Agranulocytosis may occur abruptly during thionamide treatment.
- Warn patients to stop the drug and seek urgent assessment for fever, sore throat or mouth ulcers.
- Request an urgent full blood count with neutrophil differential; a total WBC alone can be misleading.
- Confirmed febrile neutropenia requires urgent sepsis evaluation and treatment.
Exam pearl: Carbimazole plus fever/sore throat: stop immediately and check neutrophils urgently.
Examiner trap: Do not simply prescribe antibiotics and continue carbimazole without evaluating neutropenia.
Viva extension: What are definitive Graves options after serious thionamide toxicity? Specialist discussion of radioactive iodine or thyroidectomy when clinically appropriate.
Q828. A 33-year-old woman has weight loss, tremor and palpitations. Her TSH is suppressed, free T4 is raised, adjusted calcium is mildly elevated and intact PTH is suppressed. What is the most likely mechanism of her hypercalcaemia?
Recorded recall sessions: May 2023
A. Thyroid-hormone-associated increased bone turnover and resorption
B. Autonomous PTH secretion from a parathyroid adenoma
C. PTH-related peptide secretion from a confirmed lung cancer
D. Excessive calcium absorption due to vitamin D intoxication
Answer and explanation
A. Thyroid-hormone-associated increased bone turnover and resorption
Thyrotoxicosis can cause mild PTH-independent hypercalcaemia through accelerated bone turnover and net skeletal calcium release. Suppressed PTH is the expected feedback response to hypercalcaemia; other causes still need consideration when findings are atypical or persistent.
B. Primary hyperparathyroidism usually shows inappropriately normal or raised PTH in hypercalcaemia.
C. PTHrP malignancy-associated hypercalcaemia requires a different clinical context; no malignancy is established.
D. Vitamin D excess is not suggested by the hyperthyroid syndrome and would require separate evidence.
- Thyrotoxicosis may cause mild hypercalcaemia with suppressed PTH.
- Marked hypercalcaemia warrants investigation for alternative or additional causes.
- Treating hyperthyroidism often normalises calcium.
- PTH is a key first discriminator in hypercalcaemia work-up.
Exam pearl: High free T4 + low TSH + mild hypercalcaemia + suppressed PTH can reflect thyroid-driven bone resorption.
Examiner trap: The original source mentioned low TSH and high calcium without free T4 or PTH, so no unique diagnosis could be established.
Viva extension: How does primary hyperparathyroidism differ? PTH is inappropriately normal or high despite elevated serum calcium.
Q835. A 32-year-old woman, who has not recently been pregnant, has a painless small goitre. She initially had suppressed TSH and raised free T4, but six weeks later develops elevated TSH and low free T4. During the thyrotoxic phase, radionuclide uptake was very low and TSH-receptor antibodies were negative. What is the most likely diagnosis?
Recorded recall sessions: September 2020
A. Graves disease
B. Toxic solitary adenoma
C. Painless (silent) thyroiditis
D. TSH-secreting pituitary adenoma
Answer and explanation
C. Painless (silent) thyroiditis
Destructive painless thyroiditis releases preformed hormone during a transient thyrotoxic phase, then may produce a hypothyroid phase as stores are depleted. Low uptake reflects suppressed new hormone synthesis; Graves disease generally has increased diffuse uptake and TSH-receptor antibodies. The absence of pain distinguishes silent thyroiditis from classic painful subacute de Quervain thyroiditis.
A. Graves usually has increased thyroid hormone synthesis and diffuse increased uptake, often with positive TRAb.
B. An autonomous toxic nodule generally produces focal increased radionuclide uptake and does not classically transition to a hypothyroid phase.
D. A TSHoma produces inappropriately normal/high TSH despite raised thyroid hormones, unlike the suppressed TSH described.
- Silent thyroiditis is often autoimmune and may have anti-TPO antibodies.
- A low radionuclide uptake during thyrotoxicosis supports destructive thyroiditis rather than Graves.
- Beta blockers relieve symptoms in the thyrotoxic phase; antithyroid drugs do not treat hormone leakage.
- Many patients recover euthyroidism, although some develop persistent hypothyroidism.
Exam pearl: Thyrotoxicosis followed by hypothyroidism + low uptake + painless gland = silent thyroiditis.
Examiner trap: Low uptake is a clue to hormone leakage, not increased synthesis; do not reflexively prescribe carbimazole.
Viva extension: Why are thionamides ineffective in destructive thyroiditis? They inhibit new hormone synthesis, whereas excess hormone is released from damaged follicles.
Q846. A 55-year-old man with a pituitary macroadenoma has fatigue, low free T4 (6 pmol/L) and an inappropriately low TSH (0.2 mIU/L). His morning cortisol result is not yet available. Before commencing levothyroxine, what is the most important endocrine safety step?
Recorded recall sessions: January 2021
A. Begin high-dose levothyroxine immediately without further assessment
B. Assess for central adrenal insufficiency and give glucocorticoid cover first if it cannot be excluded
C. Administer radioiodine to suppress residual thyroid tissue
D. Treat with carbimazole to normalise TSH
Answer and explanation
B. Assess for central adrenal insufficiency and give glucocorticoid cover first if it cannot be excluded
Low free T4 with inappropriately low or normal TSH in pituitary disease indicates central hypothyroidism. Concomitant ACTH deficiency must be assessed before thyroid replacement, because levothyroxine increases cortisol clearance and metabolic demand and can precipitate adrenal crisis. If adrenal insufficiency is possible and cannot promptly be excluded, give appropriate glucocorticoid cover before thyroid hormone.
A. Unprotected thyroid replacement may precipitate an adrenal crisis in coexistent ACTH deficiency.
C. Radioiodine has no role in central hypothyroidism.
D. Carbimazole suppresses thyroid synthesis and would worsen hypothyroidism.
- Central hypothyroidism is diagnosed using free T4 with an inappropriately low/normal TSH.
- A normal TSH does not exclude central hypothyroidism.
- Exclude or treat cortisol deficiency before levothyroxine.
- Monitor free T4, not TSH alone, when titrating replacement in central disease.
Exam pearl: In suspected hypopituitarism: cortisol first, then thyroxine.
Examiner trap: The original recall tested recognition of secondary hypothyroidism; this is a distinct management-safety objective, not another biochemical diagnosis question.
Viva extension: Why can TSH be misleading during treatment? Pituitary TSH secretion is deficient, so free T4 is the principal replacement-monitoring marker.
Q866. A 26-year-old woman at 20 weeks of pregnancy has Graves disease controlled on a low dose of antithyroid medication. Her TSH-receptor antibodies remain markedly elevated at more than three times the assay upper limit. What additional assessment is most appropriate?
Recorded recall sessions: January 2021
A. Routine radioiodine uptake scanning in the mother
B. Stop all thyroid and fetal surveillance because maternal free T4 is controlled
C. Immediate fetal thyroidectomy
D. Coordinate specialist fetal ultrasound surveillance for fetal thyroid dysfunction and growth
Answer and explanation
D. Coordinate specialist fetal ultrasound surveillance for fetal thyroid dysfunction and growth
Maternal TSH-receptor antibodies cross the placenta and can stimulate the fetal thyroid even when maternal hormone concentrations are controlled, including after maternal definitive thyroid treatment. Markedly elevated TRAb warrants obstetric–endocrine collaboration and fetal monitoring for tachycardia, growth restriction and goitre, with maternal treatment titrated to avoid fetal hypothyroidism.
A. Radioiodine imaging is contraindicated in pregnancy.
B. Controlled maternal thyroid hormones do not eliminate risk from circulating stimulating TRAb.
C. Fetal thyroidectomy is not an appropriate treatment for this scenario.
- TRAb can cross the placenta and cause fetal or neonatal hyperthyroidism.
- Check TRAb in pregnant patients with current or previous Graves disease as recommended.
- High maternal TRAb prompts targeted fetal surveillance.
- Use the lowest effective antithyroid dose and monitor maternal thyroid function.
Exam pearl: High maternal TRAb can endanger the fetus despite normal maternal free T4.
Examiner trap: Do not confuse maternal biochemical euthyroidism with absence of fetal risk.
Viva extension: What fetal signs suggest thyrotoxicosis? Persistent tachycardia, goitre, growth restriction and advanced bone maturation.
Q869. A 52-year-old with untreated Graves disease develops fever, agitation, atrial fibrillation and severe tachycardia after an infection. A thyroid storm treatment bundle includes beta-blockade, glucocorticoids, a thionamide and inorganic iodine. Which sequence is correct?
Recorded recall sessions: September 2019; 2022/2023 (mixed/uncertain session); January 2023; April 2026
A. Give iodine first and a thionamide 24 hours later
B. Use iodine alone because it permanently blocks thyroid hormone synthesis
C. Give a thionamide first, followed by iodine at least about one hour later
D. Delay all antithyroid therapy until TSH returns to normal
Answer and explanation
C. Give a thionamide first, followed by iodine at least about one hour later
Thionamides inhibit thyroid hormone synthesis and should precede inorganic iodine in the conventional thyroid storm regimen. Iodine given after the thionamide (typically at least an hour later) acutely suppresses hormone release while avoiding supplying substrate for additional hormone synthesis before blockade. Concurrent supportive care, beta-blockade when safe, glucocorticoids and treatment of the precipitant are essential.
A. Iodine first may provide substrate for new hormone synthesis and reverses the conventional sequence.
B. Iodine is short-term adjunctive therapy, not definitive monotherapy.
D. Thyroid storm is a clinical emergency; do not delay treatment for repeat TSH testing.
- Thyroid storm is a clinical diagnosis with multisystem decompensation.
- Start supportive care and treat precipitating infection or other trigger.
- Thionamide precedes iodine by at least approximately one hour in standard protocols.
- Glucocorticoids reduce peripheral T4-to-T3 conversion and address relative adrenal insufficiency.
Exam pearl: Thyroid storm sequence: thionamide first, iodine later.
Examiner trap: Do not give iodine before blocking new thyroid hormone synthesis.
Viva extension: When is beta-blockade hazardous? In decompensated heart failure or shock, use careful haemodynamic assessment and specialist titration.
Q872. A 35-year-old woman relapses after an adequate antithyroid-drug course. She has active, severe Graves orbitopathy with diplopia and inflammatory eye signs. Which statement best guides definitive thyroid treatment?
Recorded recall sessions: September 2021
A. Radioiodine is automatically preferred because it improves active orbitopathy
B. Radioiodine is generally avoided in active severe orbitopathy; thyroidectomy after appropriate preparation is an important option
C. Orbitopathy has no bearing on the choice of thyroid therapy
D. Long-term untreated thyrotoxicosis is safer than any definitive treatment
Answer and explanation
B. Radioiodine is generally avoided in active severe orbitopathy; thyroidectomy after appropriate preparation is an important option
Radioiodine can exacerbate Graves orbitopathy, especially in active or severe eye disease, and is generally contraindicated in active severe orbitopathy. For relapsed Graves disease, specialist discussion includes antithyroid medication and definitive surgery after achieving adequate preparation. Eye disease needs parallel ophthalmology/endocrine management.
A. Radioiodine may worsen active eye disease rather than reliably improve it.
C. Activity and severity of orbitopathy directly affect treatment choice.
D. Persistent uncontrolled hyperthyroidism has significant cardiovascular and systemic risks.
- Relapse after antithyroid drugs prompts discussion of definitive treatment or selected long-term medical therapy.
- Active severe orbitopathy is a major reason to avoid radioiodine.
- Achieve biochemical control before elective thyroidectomy when feasible.
- Coordinate management with ophthalmology for sight-threatening or active eye disease.
Exam pearl: Active severe Graves orbitopathy → avoid radioiodine; consider surgery.
Examiner trap: Do not assume radioiodine is the default for every relapse.
Viva extension: What other factors favour surgery? Large compressive goitre, suspected malignancy or a need for rapid definitive control.
Q969. A 55-year-old recovering from severe pneumonia has TSH 6.2 mIU/L (reference 0.4–4.0), normal free T4 and mildly reduced total T3. She has no goitre, thyroid medication or previous abnormal thyroid results. What is the most appropriate interpretation and next step?
Recorded recall sessions: September 2019
A. Diagnose Graves disease and start carbimazole
B. Diagnose central hypothyroidism solely because T3 is low
C. Start high-dose levothyroxine immediately based on a single mildly raised TSH
D. The pattern may reflect recovery from non-thyroidal illness; repeat TSH and free T4 after recovery before labelling persistent hypothyroidism
Answer and explanation
D. The pattern may reflect recovery from non-thyroidal illness; repeat TSH and free T4 after recovery before labelling persistent hypothyroidism
Non-thyroidal illness can reduce circulating T3, and TSH may transiently rise during recovery. A mildly raised TSH with normal free T4 can also be subclinical hypothyroidism, but a single measurement in recent severe illness should be repeated after recovery before diagnosing a persistent disorder.
A. Graves disease usually suppresses TSH and raises free T4 and/or T3 rather than causing this pattern.
B. Central hypothyroidism generally features low free T4 with an inappropriately low or normal TSH; isolated low T3 during illness is non-specific.
C. Transient TSH elevation may occur during recovery; persistent biochemical abnormality and clinical context should be established first.
- Low T3 is common in non-thyroidal illness and is not by itself proof of primary thyroid failure.
- A high TSH with normal free T4 may represent subclinical hypothyroidism if persistent.
- Repeat tests when the patient is clinically well, often after approximately six weeks or longer.
- Evaluate medication effects, thyroid antibodies and symptoms if abnormalities persist.
Exam pearl: Low T3 after severe illness does not automatically require thyroid replacement.
Examiner trap: The original recall had high TSH, normal T4 and low T3 without clinical context; it cannot reliably distinguish recovery from persistent subclinical hypothyroidism.
Viva extension: What is the biochemical definition of overt primary hypothyroidism? Elevated TSH with low free T4.
Q976. A stable 55-year-old outpatient has fatigue, TSH 0.2 mIU/L (reference 0.4–4.3) and free T4 6 pmol/L (reference 9–26). He is not acutely ill and takes no thyroid-suppressing medication. What is the most likely endocrine pattern?
Recorded recall sessions: January 2021
A. Primary overt hypothyroidism.
B. Central hypothyroidism due to inadequate pituitary or hypothalamic TSH drive.
C. Subclinical primary hypothyroidism.
D. Primary thyrotoxicosis.
Answer and explanation
B. Central hypothyroidism due to inadequate pituitary or hypothalamic TSH drive.
Low free T4 should normally stimulate TSH secretion. A low or inappropriately normal TSH in the presence of low free T4 indicates a central defect, provided assay interference, medication effects and non-thyroidal illness are excluded.
A. Primary gland failure normally produces a raised TSH with low free T4.
C. This requires raised TSH with free T4 within the reference interval.
D. Thyrotoxicosis generally suppresses TSH while raising free T4 and/or free T3.
- Evaluate other pituitary axes and consider pituitary imaging when appropriate.
- Check adrenal function before levothyroxine if ACTH deficiency is possible.
- TSH is unreliable for dose titration in established central hypothyroidism.
- Severe illness, glucocorticoids and assay interference can mimic this pattern.
Exam pearl: Low FT4 plus low or inappropriately normal TSH suggests central hypothyroidism.
Examiner trap: Never start thyroid hormone in suspected combined pituitary failure without addressing possible cortisol deficiency.
Viva extension: How is replacement monitored? Mainly with free T4 and clinical assessment, rather than TSH alone.
Q31. Following treatment of differentiated papillary thyroid carcinoma, which serum marker is useful for surveillance in a suitably treated patient?
Recorded recall sessions: September 2018
A. Calcitonin
B. Alpha-fetoprotein
C. Thyroglobulin
D. Carcinoembryonic antigen
Answer and explanation
C. Thyroglobulin
Thyroglobulin is produced by differentiated thyroid follicular cells and serves as a disease marker after total thyroidectomy, often with radioactive iodine according to risk. Interpretation requires checking thyroglobulin antibodies and residual thyroid tissue.
A. Mainly marks medullary thyroid carcinoma arising from parafollicular C cells.
B. Associated with hepatocellular and certain germ-cell tumours.
D. May rise in medullary thyroid carcinoma but is not the standard differentiated-thyroid surveillance marker.
- Ultrasound is a key complement to serum surveillance
- Anti-thyroglobulin antibodies interfere with measurement
- Calcitonin is important in medullary disease.
Exam pearl: Papillary/follicular cancer follow-up: thyroglobulin; medullary: calcitonin.
Examiner trap: Thyroglobulin is not a specific cancer marker if normal thyroid tissue remains.
Viva extension: Which additional blood test accompanies thyroglobulin? Anti-thyroglobulin antibodies.
Q32. Which route of spread is most characteristic of papillary thyroid carcinoma?
Recorded recall sessions: September 2022
A. Direct spread to the brain as the usual first site
B. Regional cervical lymphatics
C. Haematogenous spread to bone as the dominant initial route
D. Peritoneal implantation
Answer and explanation
B. Regional cervical lymphatics
Papillary thyroid carcinoma has a strong tendency to spread to regional cervical lymph nodes, sometimes despite a small primary tumour. Follicular carcinoma more often spreads haematogenously to bone and lung.
A. Brain metastasis is uncommon and is not the characteristic route.
C. More classically associated with follicular thyroid carcinoma.
D. Not a typical spread pattern of thyroid cancer.
- Papillary histology includes nuclear clearing, grooves and inclusions
- Follicular carcinoma requires capsular or vascular invasion for histological diagnosis
- Management is risk-adapted rather than automatically radical.
Exam pearl: Papillary thyroid cancer: lymph nodes; follicular: bloodstream.
Examiner trap: Do not diagnose follicular carcinoma using FNAC alone because vascular or capsular invasion cannot be assessed.
Viva extension: Which neck node levels may be involved? Central compartment VI and lateral cervical chains.
Q33. A woman has biopsy-proven medullary thyroid carcinoma with clinically involved cervical lymph nodes. What is the definitive operative principle?
Recorded recall sessions: January 2018
A. Thyroid lobectomy alone
B. Subtotal thyroidectomy
C. Radioactive iodine ablation as sole treatment
D. Total thyroidectomy with appropriate compartment-oriented nodal dissection
Answer and explanation
D. Total thyroidectomy with appropriate compartment-oriented nodal dissection
Medullary thyroid cancer originates from parafollicular C cells, and definitive treatment is total thyroidectomy with nodal surgery according to involved compartments. Before operating, screen for associated phaeochromocytoma and assess germline RET status.
A. Insufficient for proven medullary cancer, particularly with nodal involvement.
B. Leaves thyroid tissue at risk and is not definitive oncological management.
C. C-cell tumours generally do not take up iodine in a therapeutically useful fashion.
- Calcitonin and CEA support surveillance
- MEN2 is associated with RET pathogenic variants
- Address phaeochromocytoma before thyroid surgery to prevent hypertensive crisis.
Exam pearl: Medullary thyroid cancer: calcitonin, RET, total thyroidectomy, nodal assessment.
Examiner trap: Never operate on MEN2-associated thyroid disease without considering phaeochromocytoma.
Viva extension: What are the MEN2A components? Medullary thyroid cancer, phaeochromocytoma and primary hyperparathyroidism.
Q34. Why can FNAC not reliably distinguish follicular thyroid adenoma from follicular carcinoma?
Recorded recall sessions: September 2017
A. Both lesions lack follicular cells
B. Serum calcitonin is always raised in carcinoma
C. Capsular or vascular invasion requires tissue architecture
D. Malignant follicular cells always show papillary nuclear inclusions
Answer and explanation
C. Capsular or vascular invasion requires tissue architecture
The distinction between follicular adenoma and carcinoma requires demonstration of capsular and/or vascular invasion in a histological specimen. Cytology can identify a follicular neoplasm but cannot evaluate the complete capsule.
A. Both consist of follicular-patterned epithelial cells.
B. Calcitonin is principally linked to medullary, not follicular, thyroid carcinoma.
D. These nuclear features are characteristic of papillary carcinoma.
- Diagnostic lobectomy may be appropriate for an indeterminate follicular-pattern nodule
- Papillary carcinoma can often be recognised from nuclear cytological features
- Ultrasound risk stratification informs further assessment.
Exam pearl: Follicular neoplasm needs histology to demonstrate invasion.
Examiner trap: A cytology report of follicular neoplasm is not proof of follicular carcinoma.
Viva extension: Which pattern is more likely in follicular carcinoma? Haematogenous spread to bone and lungs.
Q35. A patient with longstanding Hashimoto thyroiditis develops a rapidly enlarging thyroid mass, shown to be lymphoma. What cell lineage is most likely?
Recorded recall sessions: January 2020; September 2020; May 2022; January 2024
A. B-lymphocyte lineage
B. T-lymphocyte lineage
C. Natural killer-cell lineage
D. Macrophage lineage
Answer and explanation
A. B-lymphocyte lineage
Primary thyroid lymphoma is strongly associated with chronic autoimmune Hashimoto thyroiditis and is usually a B-cell non-Hodgkin lymphoma, commonly diffuse large B-cell or MALT type.
B. Possible but much less characteristic than B-cell primary thyroid lymphoma.
C. Not the usual lineage of lymphoma arising in Hashimoto thyroiditis.
D. Lymphoma is a lymphoid malignancy, not a macrophage-derived sarcoma.
- Rapid thyroid enlargement may cause compressive symptoms
- Core biopsy and immunophenotyping establish diagnosis
- Treatment is commonly haematological rather than routine thyroidectomy.
Exam pearl: Hashimoto thyroiditis is a risk factor for primary thyroid B-cell lymphoma.
Examiner trap: Rapidly enlarging thyroid masses may also represent anaplastic carcinoma; tissue diagnosis matters.
Viva extension: What histological types are common? DLBCL and extranodal marginal-zone/MALT lymphoma.
Q84. After thyroidectomy for medullary thyroid carcinoma, which listed serum marker is useful for surveillance when calcitonin is not among the choices?
Recorded recall sessions: September 2022
A. Carcinoembryonic antigen (CEA)
B. Thyroglobulin
C. Thyroid-stimulating hormone
D. Thyroxine (T4)
Answer and explanation
A. Carcinoembryonic antigen (CEA)
Medullary thyroid carcinoma arises from parafollicular C cells and usually secretes calcitonin; calcitonin and CEA are the standard markers used together to follow biochemical disease burden. CEA is the best answer from this source option set because calcitonin is absent.
B. Used mainly for differentiated papillary and follicular thyroid carcinoma follow-up, not C-cell cancer.
C. Useful for assessing thyroid replacement but not a specific medullary tumour marker.
D. Measures thyroid hormone replacement status rather than residual medullary cancer.
- Assess for RET-associated hereditary syndromes
- Calcitonin is generally the primary biochemical marker
- Thyroglobulin surveillance belongs to follicular-derived differentiated thyroid cancer
Exam pearl: Medullary cancer follow-up: calcitonin plus CEA.
Examiner trap: If calcitonin is an option, do not assume CEA is the sole or preferred marker.
Viva extension: What germline gene is associated with MEN2 and familial medullary cancer? RET.
Q177. A 26-year-old woman has biopsy-proven medullary thyroid carcinoma and confirmed ipsilateral lateral cervical lymph-node metastases, with no distant disease. What is the most appropriate operative strategy?
Recorded recall sessions: September 2018; April 2021
A. Hemithyroidectomy alone
B. Radioiodine ablation alone
C. Subtotal thyroidectomy without nodal surgery
D. Total thyroidectomy with central and therapeutic involved lateral-neck compartment dissection
Answer and explanation
D. Total thyroidectomy with central and therapeutic involved lateral-neck compartment dissection
Medullary thyroid carcinoma arises from calcitonin-producing parafollicular C cells. With confirmed regional nodal spread and no prohibitive distant disease, standard management involves total thyroidectomy, central compartment clearance and therapeutic dissection of clinically involved lateral nodal levels.
A. MTC may be multifocal or hereditary and nodal metastases require more extensive disease-directed treatment.
B. MTC arises from parafollicular C cells and is not treated with radioactive iodine like iodine-avid differentiated cancers.
C. This leaves thyroid tissue and known metastatic nodes untreated.
- Obtain calcitonin and CEA for baseline and follow-up.
- Assess RET mutation status and possible MEN2.
- Exclude pheochromocytoma before thyroid surgery when hereditary MTC is suspected.
- Therapeutic lateral dissection targets clinically involved compartments; not a radical neck dissection by default.
Exam pearl: MTC with involved lateral nodes = total thyroidectomy plus compartment-oriented node dissection.
Examiner trap: Exclude MEN2-associated pheochromocytoma before proceeding to thyroidectomy.
Viva extension: Which tumour markers monitor MTC? Calcitonin and CEA.
Q180. A 40-year-old man with a thyroid nodule has episodic headache, palpitations, sweating and blood pressure of 200/120 mmHg. Which endocrine tumour must be excluded before thyroid surgery?
Recorded recall sessions: April 2017; September 2019; January 2021; April 2021
A. Primary hyperparathyroidism
B. Conn syndrome
C. Phaeochromocytoma
D. Cushing syndrome
Answer and explanation
C. Phaeochromocytoma
Catecholamine-secreting adrenal medullary tumours produce paroxysmal headache, sweating and palpitations with severe or labile hypertension. In a patient with possible MEN2-related thyroid disease, phaeochromocytoma should be excluded and, if present, treated before thyroidectomy to avoid a catecholamine crisis.
A. This causes PTH-mediated calcium abnormalities and does not typically produce paroxysmal catecholamine symptoms.
B. Primary aldosteronism causes hypertension, often with hypokalaemia, but not the classic episodic triad.
D. Cortisol excess can cause hypertension but usually presents with chronic metabolic and characteristic physical features.
- Screen with plasma free metanephrines or appropriate urinary fractionated metanephrines.
- MEN2 can combine medullary thyroid cancer with phaeochromocytoma.
- If surgery is indicated, alpha blockade precedes beta blockade.
- Biopsy of an unsuspected adrenal phaeochromocytoma is dangerous.
Exam pearl: Headache + sweating + palpitations + hypertension = consider phaeochromocytoma.
Examiner trap: Never initiate isolated beta blockade before adequate alpha blockade in a confirmed catecholamine-secreting tumour.
Viva extension: Which tumour must be managed first in MEN2? Phaeochromocytoma, before thyroid surgery.
Q181. A euthyroid 42-year-old woman has an asymptomatic 2-cm thyroid nodule. Ultrasound is low-risk and ultrasound-guided cytology is benign (Thy2/Bethesda II). What is the best initial management?
Recorded recall sessions: April 2021; April 2026
A. Immediate total thyroidectomy
B. Radioiodine ablation for all benign nodules
C. Routine open incisional biopsy
D. Conservative management with ultrasound-based risk assessment and follow-up as indicated
Answer and explanation
D. Conservative management with ultrasound-based risk assessment and follow-up as indicated
Benign cytology in a low-risk, asymptomatic thyroid nodule supports nonoperative management. Follow-up depends on ultrasound risk features, size, growth and clinical concern; selected very-low-risk nodules may need no further routine imaging.
A. Benign cytology without compression or suspicious imaging does not justify routine total thyroidectomy.
B. Radioiodine is not routine treatment for an asymptomatic benign euthyroid nodule.
C. Open biopsy is unnecessary after reassuring clinical, ultrasound and cytological assessment.
- Thyroid ultrasound assesses composition, margins, echogenicity and suspicious nodes.
- Discordance between benign cytology and suspicious imaging requires reassessment.
- Rapid growth, compressive symptoms or suspicious nodes change management.
- Thy2 (UK) and Bethesda II describe benign cytological categories.
Exam pearl: Benign low-risk thyroid nodule = observation, not automatic surgery.
Examiner trap: Do not discharge a suspicious ultrasound lesion solely because a single FNA is benign.
Viva extension: What warrants repeat assessment? Growth, new symptoms or discordant suspicious ultrasound findings.
Q184. A woman with a thyroid nodule and cervical lymphadenopathy undergoes FNAC. Cells have optically clear nuclei, nuclear grooves and intranuclear pseudoinclusions. Which diagnosis is most strongly suggested?
Recorded recall sessions: January 2020; September 2020; 2022/2023 (mixed/uncertain session); January 2024; September 2024; January 2025
A. Follicular thyroid adenoma
B. Medullary thyroid carcinoma
C. Papillary thyroid carcinoma
D. Primary thyroid lymphoma
Answer and explanation
C. Papillary thyroid carcinoma
Papillary thyroid carcinoma commonly demonstrates optically clear Orphan Annie-eye nuclei, grooves and intranuclear cytoplasmic pseudoinclusions, often with papillary architecture and psammoma bodies.
A. Follicular adenoma has a follicular pattern without the characteristic combination of papillary carcinoma nuclear features.
B. Medullary carcinoma derives from C cells and may show amyloid stroma and calcitonin positivity.
D. Thyroid lymphoma shows a lymphoid infiltrate, frequently in a background of Hashimoto thyroiditis.
- Papillary thyroid cancer often spreads via lymphatics to cervical nodes.
- Nuclear grooves alone are not diagnostic; assess the full cytological pattern.
- Psammoma bodies are laminated calcifications that can support the diagnosis.
- Definitive management depends on tumour size, risk and nodal status.
Exam pearl: Clear nuclei + grooves + pseudoinclusions = papillary thyroid carcinoma.
Examiner trap: Nuclear grooves may appear in benign thyroid lesions; do not diagnose from one feature alone.
Viva extension: How does follicular thyroid carcinoma differ in its route of spread? Haematogenous spread is more characteristic.
Q319. A 72-year-old woman develops a rapidly enlarging hard thyroid mass over three weeks with stridor, dysphagia and hoarseness. Cytology shows highly pleomorphic spindle and giant malignant cells. Which diagnosis is most likely?
Recorded recall sessions: January 2017; September 2017; January 2018; September 2020; September 2021; 2021 (session not specified); May 2022
A. Papillary thyroid carcinoma
B. Anaplastic thyroid carcinoma
C. Follicular thyroid adenoma
D. Medullary thyroid carcinoma
Answer and explanation
B. Anaplastic thyroid carcinoma
Anaplastic thyroid carcinoma is a highly aggressive undifferentiated thyroid malignancy, often in older adults, causing rapid local invasion and compressive airway symptoms. Urgent airway evaluation and multidisciplinary oncological management are essential.
A. Usually has distinctive papillary nuclear features and typically does not cause such explosive compressive progression.
C. A benign encapsulated follicular lesion does not invade the airway or produce pleomorphic malignant spindle cells.
D. Arises from parafollicular C cells and may show calcitonin positivity or amyloid stroma, not the classic rapidly destructive undifferentiated picture.
- Rapid progression, pain, dysphagia and voice change are warning signs.
- Histology may contain pleomorphic spindle or giant cells.
- Assess airway stability before lengthy outpatient investigations.
- Molecular testing, including BRAF V600E when relevant, can affect systemic treatment.
Exam pearl: Elderly patient + rapidly enlarging thyroid mass + stridor = suspect anaplastic carcinoma.
Examiner trap: A negative cervical-node examination does not exclude aggressive thyroid malignancy.
Viva extension: What is the immediate priority with stridor? Airway assessment and a specialist rescue plan.
Q324. A 58-year-old woman has a thyroid follicular-pattern malignancy with destructive metastases in the femur and multiple pulmonary nodules. Which thyroid cancer classically spreads haematogenously to bone and lung?
Recorded recall sessions: January 2020; May 2022
A. Papillary thyroid carcinoma
B. Medullary thyroid carcinoma
C. Follicular thyroid carcinoma
D. Primary thyroid lymphoma
Answer and explanation
C. Follicular thyroid carcinoma
Follicular thyroid carcinoma is defined by capsular and/or vascular invasion and commonly spreads through blood vessels to bone and lung. Cytology alone cannot reliably distinguish follicular adenoma from carcinoma because invasion must be assessed histologically.
A. Papillary carcinoma more commonly spreads initially through lymphatics to cervical nodes, although distant metastases can occur.
B. A C-cell tumour that may metastasise widely but is not the classic follicular-pattern haematogenous-spread answer.
D. A lymphoid tumour rather than a follicular epithelial thyroid carcinoma, with different pathology and patterns of spread.
- Follicular thyroid carcinoma may produce functioning metastases in selected cases.
- Papillary carcinoma preferentially spreads to cervical lymph nodes.
- Fine-needle cytology cannot demonstrate capsular or vascular invasion.
- Staging and treatment depend on disease burden and risk category.
Exam pearl: Follicular = haematogenous; papillary = lymphatic is a useful exam contrast, not an absolute rule.
Examiner trap: The original recall wording was corrupted; a coherent metastatic scenario was reconstructed.
Viva extension: Why cannot FNAC reliably distinguish follicular adenoma from carcinoma? Invasion requires examination of the capsule and vessels.
Q327. A tall, slender 25-year-old woman has mucosal neuromas on the lips and tongue, medullary thyroid carcinoma, episodic headache, palpitations and blood pressure 220/120 mmHg. Which associated lesion best explains her severe hypertension?
Recorded recall sessions: September 2017; September 2018; January 2021; May 2022
A. Adrenal phaeochromocytoma
B. Primary aldosteronism
C. ACTH-secreting pituitary adenoma
D. Renal artery fibromuscular dysplasia
Answer and explanation
A. Adrenal phaeochromocytoma
MEN2B is a RET-associated syndrome featuring medullary thyroid carcinoma, mucosal neuromas and a marfanoid habitus. Catecholamine-secreting phaeochromocytoma causes paroxysmal or sustained hypertension, headache, sweating and palpitations. Confirm biochemically with plasma free or urinary fractionated metanephrines; treat the phaeochromocytoma with appropriate alpha blockade and surgery before thyroid surgery.
B. Primary aldosteronism causes hypertension with suppressed renin and sometimes hypokalaemia, not the MEN2B triad.
C. Cushing disease may cause hypertension but does not explain mucosal neuromas or RET-associated medullary cancer.
D. Fibromuscular dysplasia may cause renovascular hypertension in young women but is not the characteristic endocrine lesion of MEN2B.
- MEN2A: medullary carcinoma, phaeochromocytoma and primary hyperparathyroidism.
- MEN2B: medullary carcinoma, phaeochromocytoma, mucosal neuromas and marfanoid habitus.
- Biochemical exclusion of phaeochromocytoma precedes thyroid surgery in MEN2.
- Alpha blockade must precede beta blockade if tachycardia also requires control.
Exam pearl: MEN2B + mucosal neuromas + hypertension = phaeochromocytoma until excluded.
Examiner trap: Never operate on medullary thyroid carcinoma before excluding an untreated catecholamine-secreting tumour.
Viva extension: What is the genetic mechanism? Germline activating RET variants; MEN2B most often involves RET M918T.
Q351. A 45-year-old woman has a solitary 5-mm intrathyroidal papillary thyroid carcinoma with no extrathyroidal extension, suspicious nodes, family history or prior radiation. After counselling about active surveillance, she elects definitive surgery. What is the recommended initial extent of thyroid surgery?
Recorded recall sessions: April 2017
A. Ipsilateral thyroid lobectomy
B. Total thyroidectomy with prophylactic lateral neck dissection
C. Subtotal thyroidectomy leaving tumour-bearing tissue
D. Routine total thyroidectomy plus radioactive iodine
Answer and explanation
A. Ipsilateral thyroid lobectomy
For a low-risk cT1aN0M0 papillary microcarcinoma, active surveillance is an acceptable option in selected patients. If surgery is chosen, current ATA guidance recommends thyroid lobectomy for cancers 2 cm or smaller without gross extrathyroidal extension or metastases unless bilateral disease or another indication for total thyroidectomy exists. Routine prophylactic lateral dissection and radioactive iodine are not indicated.
B. Lateral neck dissection is reserved for appropriate proven nodal disease, not prophylaxis in a clinically node-negative microcarcinoma.
C. Subtotal thyroidectomy is not an oncologically appropriate way to leave part of a known tumour-bearing lobe.
D. Total thyroidectomy and radioactive iodine would overtreat this otherwise low-risk 5-mm lesion.
- Papillary microcarcinoma is papillary carcinoma 1 cm or smaller.
- Active surveillance may be offered to selected low-risk cT1aN0M0 patients.
- When surgery is chosen for low-risk disease 2 cm or smaller, lobectomy is the preferred initial operation.
- Higher-risk features or bilateral disease can change the extent of surgery.
Exam pearl: Low-risk 5-mm papillary carcinoma: surveillance may be appropriate; if operating, lobectomy.
Examiner trap: The source recall implied immediate surgery; the reconstructed question explicitly establishes the patient has chosen surgery after discussing surveillance.
Viva extension: When is total thyroidectomy favoured? Gross extrathyroidal extension, significant nodal/distant disease or other specific bilateral/high-risk indications.
Q510. A 50-year-old has biopsy-proven 2-cm medullary thyroid carcinoma with elevated calcitonin. Neck ultrasound shows no suspicious nodes and staging shows no distant disease. After appropriate MEN2 and phaeochromocytoma assessment, which initial operation is recommended by ATA guidance?
Recorded recall sessions: September 2019
A. Total thyroidectomy with central compartment (level VI) lymph-node dissection
B. Hemithyroidectomy alone without nodal assessment
C. Radioactive iodine ablation without surgery
D. Routine bilateral lateral neck dissection in every node-negative case
Answer and explanation
A. Total thyroidectomy with central compartment (level VI) lymph-node dissection
Medullary thyroid carcinoma arises from parafollicular C cells and can spread to central cervical nodes even without imaging-detected disease. ATA guidance recommends total thyroidectomy with central-compartment dissection for MTC without detected nodal or distant metastases.
B. For a 2-cm MTC this would usually be insufficient definitive surgery.
C. MTC C cells do not meaningfully concentrate radioiodine.
D. Lateral dissection is individualised according to calcitonin and imaging rather than automatically performed in all cases.
- Check RET mutation status and consider MEN2-associated phaeochromocytoma.
- Exclude or treat phaeochromocytoma before thyroid surgery when present.
- Calcitonin and CEA are useful follow-up markers.
- Medullary cancer is not treated by radioiodine.
Exam pearl: MTC: total thyroidectomy and central level-VI dissection; lateral compartments are risk-adapted.
Examiner trap: Missing a MEN2-associated phaeochromocytoma before surgery can cause a hypertensive crisis.
Viva extension: What are MTC tumour markers? Calcitonin and carcinoembryonic antigen.
Q531. A 40-year-old has a painful fluctuant thyroid nodule. Fine-needle aspirate yields old blood with numerous haemosiderin-laden macrophages and benign follicular cells. What is the most likely explanation?
Recorded recall sessions: May 2022; May 2023; April 2025; April 2026
A. Haemorrhage into a thyroid cyst
B. Medullary thyroid carcinoma
C. Anaplastic thyroid carcinoma
D. Graves disease
Answer and explanation
A. Haemorrhage into a thyroid cyst
Siderophages are macrophages containing haemosiderin from previous haemorrhage. Old blood and benign follicular cells in a cystic thyroid nodule favour a haemorrhagic thyroid cyst.
B. Medullary carcinoma would require malignant C-cell cytology and appropriate calcitonin assessment, not siderophages alone.
C. Anaplastic carcinoma typically produces a rapidly enlarging hard aggressive mass with malignant pleomorphic cells.
D. Graves disease causes diffuse hyperfunction rather than a solitary blood-filled cyst.
- Siderophages indicate prior haemorrhage.
- Ultrasound characterises solid and cystic thyroid components.
- A suspicious residual solid component requires targeted sampling.
- Thyroid nodule evaluation also includes serum TSH and risk-based ultrasound assessment.
Exam pearl: Blood-stained thyroid aspirate with siderophages suggests a haemorrhagic cyst.
Examiner trap: Cystic degeneration does not automatically exclude thyroid malignancy if suspicious solid tissue remains.
Viva extension: When should a thyroid cyst be re-evaluated? If it recurs, has suspicious ultrasound features or contains a persistent solid component.
Q562. A 45-year-old woman has a 2-cm thyroid nodule, normal thyroid function and benign Bethesda II cytology. She has no compressive symptoms or suspicious lymph nodes. Which plan is most appropriate?
Recorded recall sessions: April 2021
A. Immediate total thyroidectomy
B. Radioiodine ablation despite euthyroidism
C. Ultrasound-based surveillance according to sonographic risk
D. Permanent discharge without any risk assessment
Answer and explanation
C. Ultrasound-based surveillance according to sonographic risk
Benign thyroid cytology in a clinically low-risk nodule generally supports observation. The ultrasound pattern guides follow-up frequency and whether repeat sampling is indicated for significant growth or new suspicious features.
A. Total thyroidectomy is excessive without malignancy, significant compression or another surgical indication.
B. Radioiodine is not routine therapy for a benign euthyroid solitary nodule.
D. Some very-low-risk nodules need little surveillance, but blanket discharge without sonographic risk assessment is inappropriate.
- Bethesda II cytology indicates benign findings with a low malignancy risk.
- Sonographic risk pattern guides surveillance intervals.
- Growth or new suspicious features may prompt repeat FNA.
- Surgery may be indicated for compression, cosmetic concerns or discordant suspicion.
Exam pearl: Benign thyroid FNA plus no symptoms generally means risk-adapted ultrasound surveillance.
Examiner trap: Benign cytology is reassuring but not a guarantee when imaging and clinical features disagree.
Viva extension: What change warrants reassessment? Significant growth, suspicious ultrasound changes or new compressive symptoms.
Q586. A patient has medullary thyroid carcinoma, episodic headache with severe hypertension, and PTH-dependent hypercalcaemia. Which hereditary syndrome best explains the combination?
Recorded recall sessions: May 2022; 2022/2023 (mixed/uncertain session); September 2024
A. MEN type 2A
B. MEN type 1
C. MEN type 2B
D. Von Hippel–Lindau disease
Answer and explanation
A. MEN type 2A
MEN2A, caused by germline activating RET variants, classically combines medullary thyroid carcinoma, phaeochromocytoma and primary hyperparathyroidism. Biochemical exclusion and management of phaeochromocytoma are essential before thyroid surgery.
B. MEN1 features parathyroid, pancreatic neuroendocrine and pituitary tumours; medullary thyroid cancer is not typical.
C. MEN2B combines medullary thyroid cancer, phaeochromocytoma, mucosal neuromas and marfanoid habitus; hyperparathyroidism is unusual.
D. VHL predisposes to phaeochromocytoma and other tumours but not the characteristic MTC–hyperparathyroidism triad.
- MEN2A is an autosomal dominant RET syndrome.
- Screen for phaeochromocytoma before operative thyroid treatment.
- RET genetic testing informs family cascade screening.
- Calcitonin is a useful MTC tumour marker.
Exam pearl: MTC + phaeochromocytoma + hyperparathyroidism = MEN2A.
Examiner trap: MEN2B has mucosal neuromas, not the usual MEN2A hyperparathyroidism pattern.
Viva extension: Which lesion must be addressed first if both phaeochromocytoma and MTC need surgery? Phaeochromocytoma, after appropriate alpha blockade.
Q598. A 33-year-old euthyroid woman has a thyroid nodule. Aspirate shows abundant thin colloid and sheets of bland follicular epithelial cells without atypia. Which diagnosis is most likely?
Recorded recall sessions: January 2020
A. Benign colloid nodule
B. Papillary thyroid carcinoma
C. Medullary thyroid carcinoma
D. Hashimoto thyroiditis
Answer and explanation
A. Benign colloid nodule
Abundant colloid with bland follicular cells favours a benign colloid nodule. Papillary carcinoma requires characteristic nuclear features; medullary carcinoma arises from parafollicular C cells; Hashimoto thyroiditis shows lymphocytic inflammation and Hürthle-cell change.
B. Papillary carcinoma shows nuclear clearing, grooves and intranuclear inclusions rather than simply abundant bland colloid.
C. Medullary carcinoma typically shows neuroendocrine cells and may have amyloid, with raised calcitonin.
D. Hashimoto thyroiditis features lymphocytes and oncocytic/Hürthle cells.
- Benign colloid nodules are common thyroid lesions.
- FNAC cannot assess capsular/vascular invasion in a follicular-patterned neoplasm.
- Ultrasound risk stratification guides aspiration and surveillance.
- Cytology must be interpreted with ultrasound and clinical findings.
Exam pearl: Abundant colloid + bland follicular cells = benign colloid nodule.
Examiner trap: The original recall lacked the correct option; all four study options are reconstructed and not authentic.
Viva extension: Why can FNAC not prove follicular carcinoma? Capsular or vascular invasion requires histological assessment of the excised lesion.
Q626. Following total thyroidectomy for medullary thyroid carcinoma, calcitonin is unavailable on a follow-up laboratory panel. Which additional serum tumour marker is most informative?
Recorded recall sessions: May 2023
A. Carcinoembryonic antigen (CEA)
B. Thyroglobulin
C. Thyroid-stimulating hormone (TSH)
D. Thyrotropin-releasing hormone (TRH)
Answer and explanation
A. Carcinoembryonic antigen (CEA)
Medullary thyroid carcinoma arises from parafollicular C cells and can secrete calcitonin and CEA. CEA assists postoperative surveillance, particularly when interpreted serially alongside calcitonin.
B. Thyroglobulin tracks differentiated follicular-cell thyroid cancers rather than medullary thyroid carcinoma.
C. TSH assesses thyroid hormone control and does not reflect medullary tumour burden.
D. TRH is a hypothalamic regulator, not a useful MTC tumour marker.
- MTC arises from thyroid parafollicular C cells.
- Calcitonin is the principal specific biochemical marker.
- CEA provides a complementary disease-burden and trend marker.
- RET germline testing is relevant to MTC evaluation and MEN2 assessment.
Exam pearl: Medullary cancer: calcitonin + CEA; differentiated thyroid cancers: thyroglobulin.
Examiner trap: Do not substitute thyroglobulin for calcitonin in medullary carcinoma surveillance.
Viva extension: Why does MTC not reliably produce thyroglobulin? It originates from C cells, not follicular epithelial cells.
Q628. A woman has a thyroid nodule and a vascular, expansile skull-bone metastasis. Which thyroid malignancy classically spreads through the bloodstream to bone?
Recorded recall sessions: January 2017; April 2017; September 2018; September 2019; September 2020; September 2024
A. Medullary thyroid carcinoma
B. Papillary thyroid carcinoma
C. Follicular thyroid carcinoma
D. Primary thyroid lymphoma
Answer and explanation
C. Follicular thyroid carcinoma
Follicular thyroid carcinoma classically invades blood vessels and spreads haematogenously to bone and lung. Papillary thyroid carcinoma more characteristically spreads via lymphatics to cervical nodes.
A. Medullary cancer may metastasise but is not the classic follicular-pattern haematogenous bone-spread association.
B. Papillary thyroid carcinoma most commonly spreads first via cervical lymphatic pathways.
D. Primary thyroid lymphoma is lymphoid tissue malignancy and is not the classic source of a vascular skull-bone metastasis.
- Follicular thyroid carcinoma is diagnosed histologically by capsular and/or vascular invasion.
- Fine-needle aspiration cannot reliably distinguish follicular adenoma from carcinoma by cytology alone.
- Common distant metastatic sites are bone and lung.
- Papillary thyroid carcinoma is associated with characteristic nuclear features and cervical lymphatic spread.
Exam pearl: Follicular = blood-borne metastasis; papillary = lymph-node spread.
Examiner trap: Do not call a follicular-pattern FNA malignant without demonstration of invasion in tissue.
Viva extension: Why is FNA insufficient to diagnose follicular carcinoma? Cytology cannot establish invasion through the tumour capsule or into vessels.
Q647. A 61-year-old woman with longstanding Hashimoto thyroiditis develops a rapidly enlarging thyroid mass and dysphagia. Core biopsy shows a monomorphic lymphoid infiltrate expressing CD20. What is the most likely diagnosis?
Recorded recall sessions: January 2024
A. Anaplastic thyroid carcinoma
B. Papillary thyroid carcinoma
C. Medullary thyroid carcinoma
D. Primary thyroid B-cell lymphoma
Answer and explanation
D. Primary thyroid B-cell lymphoma
Rapid thyroid enlargement in a patient with Hashimoto thyroiditis, together with CD20-positive lymphoid cells, strongly suggests primary thyroid B-cell lymphoma, often diffuse large B-cell lymphoma or MALT lymphoma. Immunophenotyped tissue biopsy is important because treatment is usually systemic lymphoma-directed therapy rather than routine thyroidectomy.
A. Anaplastic carcinoma can enlarge rapidly and compress the airway but is an epithelial tumour, not a CD20-positive B-cell lymphoid neoplasm.
B. Papillary carcinoma typically shows characteristic nuclear clearing, grooves and pseudoinclusions rather than a monomorphic B-cell infiltrate.
C. Medullary carcinoma arises from parafollicular C cells and expresses calcitonin, not the typical CD20 B-cell phenotype.
- Hashimoto thyroiditis is a major risk factor for primary thyroid lymphoma.
- CD20 is a B-cell surface marker used in lymphoma immunophenotyping.
- Core biopsy with immunohistochemistry may be necessary when FNAC cannot reliably subtype the lesion.
- Assess airway compromise urgently when compressive symptoms are progressive.
- Treatment depends on lymphoma subtype and stage, often rituximab-containing therapy with or without radiotherapy.
Exam pearl: Rapidly enlarging Hashimoto goitre plus CD20-positive cells suggests primary thyroid lymphoma.
Examiner trap: Do not assume every rapidly enlarging thyroid mass is anaplastic carcinoma; immunophenotyping changes treatment.
Viva extension: Why is routine thyroidectomy not the usual definitive treatment? Primary thyroid lymphoma is managed according to histological subtype and stage, usually with lymphoma-directed systemic treatment rather than gland excision.
Q669. A 40-year-old man has a solid thyroid nodule with suspicious ultrasound features and normal TSH. Which investigation most directly provides cytological assessment for malignancy risk?
Recorded recall sessions: September 2019; September 2020; April 2021; September 2021; September 2022; 2022/2023 (mixed/uncertain session)
A. Serum thyroxine alone
B. CT of the neck
C. Radioiodine uptake scan
D. Ultrasound-guided fine-needle aspiration cytology
Answer and explanation
D. Ultrasound-guided fine-needle aspiration cytology
Ultrasound-guided FNAC samples cells from a nodule that meets size and sonographic risk criteria and is the principal cytological investigation. Ultrasound and TSH guide the decision to sample; cytology is not indicated indiscriminately for every thyroid nodule.
A. Thyroid hormones assess function but cannot reliably distinguish benign from malignant nodules.
B. CT may help assess substernal extension or invasion but does not provide cytological diagnosis.
C. Radionuclide imaging is primarily useful in selected patients with suppressed TSH to identify a functioning nodule.
- Initial thyroid-nodule assessment generally includes TSH and ultrasound.
- FNAC is chosen according to sonographic risk and size thresholds.
- A follicular neoplasm cannot be classified adenoma versus carcinoma on cytology alone; capsular/vascular invasion requires histology.
- A low TSH prompts consideration of radionuclide scanning before routine biopsy.
Exam pearl: For a suspicious euthyroid thyroid nodule, ultrasound-guided FNAC is the diagnostic tissue test.
Examiner trap: Do not use FNAC as the automatic first test for every thyroid nodule; consider TSH and ultrasound risk stratification.
Viva extension: Why can FNAC not prove follicular carcinoma? Capsular or vascular invasion must be demonstrated histologically.
Q726. A 44-year-old woman has a thyroid nodule and raised serum calcitonin. Core histology shows nests of neuroendocrine-appearing cells with eosinophilic extracellular material that stains with Congo red. Which histological feature most strongly supports medullary thyroid carcinoma?
Recorded recall sessions: January 2020; January 2023
A. Orphan Annie-eye nuclei and psammoma bodies
B. Amyloid deposition in the tumour stroma
C. Capsular and vascular invasion of uniform follicles
D. Sheets of anaplastic giant cells with extensive necrosis
Answer and explanation
B. Amyloid deposition in the tumour stroma
Medullary thyroid carcinoma arises from parafollicular C cells, produces calcitonin and commonly contains extracellular amyloid derived from altered calcitonin-related peptides. Congo red-positive amyloid stroma is a classic histological clue. RET testing and screening for MEN2-associated phaeochromocytoma are important when clinically appropriate.
A. Orphan Annie-eye nuclei, grooves and psammoma bodies characterise papillary thyroid carcinoma.
C. Capsular or vascular invasion is the key histological distinction for follicular carcinoma versus follicular adenoma.
D. Marked pleomorphism, giant cells and necrosis suggest anaplastic thyroid carcinoma.
- Medullary carcinoma is derived from neural-crest-related parafollicular C cells.
- Tumour cells are often positive for calcitonin and neuroendocrine markers.
- Amyloid stroma is Congo red-positive and shows apple-green birefringence under polarised light.
- RET-associated familial cases require MEN2 assessment; exclude phaeochromocytoma before thyroid surgery.
- Serum calcitonin and CEA are useful postoperative markers.
Exam pearl: Medullary thyroid cancer = C cells + calcitonin + amyloid stroma.
Examiner trap: Do not confuse amyloid in medullary carcinoma with the nuclear features of papillary carcinoma.
Viva extension: Which genetic syndrome is associated with medullary thyroid cancer and phaeochromocytoma? MEN2A or MEN2B caused by germline RET variants.
Q749. A 43-year-old woman undergoes thyroid lobectomy for a 3.2-cm oncocytic nodule. Histology shows a predominantly encapsulated tumour of large cells with abundant granular eosinophilic cytoplasm, with unequivocal tumour penetration through the capsule and focal vascular invasion. What is the most accurate diagnosis?
Recorded recall sessions: May 2022
A. Hürthle cell adenoma
B. Papillary thyroid carcinoma
C. Oncocytic (Hürthle cell) carcinoma
D. Medullary thyroid carcinoma
Answer and explanation
C. Oncocytic (Hürthle cell) carcinoma
Oncocytic/Hürthle cells have abundant mitochondria and granular eosinophilic cytoplasm. Capsular and/or vascular invasion distinguishes oncocytic carcinoma from oncocytic adenoma in a resection specimen. Cytology or oncocytic morphology alone cannot establish malignancy. The source listed oxyphil cells but did not supply invasion or the correct oncocytic tumour option.
A. Adenoma lacks unequivocal capsular or vascular invasion.
B. Papillary carcinoma is diagnosed by characteristic nuclear features, not merely oncocytic cytoplasm and capsular invasion.
D. Medullary carcinoma arises from parafollicular C cells and is associated with calcitonin production and amyloid-rich stroma.
- Oncocytic cytoplasm is granular and eosinophilic because of abundant mitochondria.
- Capsular or vascular invasion supports carcinoma in an oncocytic neoplasm.
- Fine-needle aspiration cannot reliably distinguish follicular-pattern adenoma from carcinoma by invasion.
- Hürthle change may also occur in Hashimoto thyroiditis.
Exam pearl: In an oncocytic thyroid neoplasm, carcinoma requires capsular and/or vascular invasion.
Examiner trap: Hürthle cells on cytology do not automatically mean Hürthle cell carcinoma.
Viva extension: Why is excision histology important? The tumour–capsule and vascular interface must be examined to demonstrate invasion.
Q772. A 32-year-old woman has a solitary 3-cm papillary thyroid carcinoma confirmed on cytology. Ultrasound shows disease confined to the right lobe, no suspicious contralateral nodules, no gross extrathyroidal extension and no abnormal cervical nodes (cT2N0M0). She prefers to minimise operative morbidity after shared decision-making. Which of the following is a guideline-concordant initial operation?
Recorded recall sessions: September 2020
A. Right thyroid lobectomy with appropriate follow-up and counselling about possible completion thyroidectomy
B. Radioactive iodine alone without surgery
C. Subtotal thyroidectomy deliberately leaving tumour-bearing tissue
D. Total thyroidectomy plus routine radical neck dissection despite no nodal disease
Answer and explanation
A. Right thyroid lobectomy with appropriate follow-up and counselling about possible completion thyroidectomy
The 2025 ATA differentiated thyroid cancer guidance allows, and may favour, lobectomy for selected unilateral low-risk 2–4-cm cT2N0M0 tumours because of lower complication burden. Total thyroidectomy may also be appropriate for selected features or patient preferences, but is not the only acceptable option. The stem explicitly states a patient preference for lower morbidity and no adverse features.
B. Radioactive iodine is not a substitute for the primary operation in this low-risk resectable tumour.
C. Subtotal resection that knowingly leaves tumour-bearing thyroid tissue is not appropriate oncologic surgery.
D. A radical neck dissection is not routine in clinically node-negative low-risk disease and adds morbidity.
- For low-risk unilateral PTC >2 to 4 cm, lobectomy or total thyroidectomy may be considered after shared decision-making.
- For tumours >4 cm, gross extrathyroidal extension or clinically involved nodes, total thyroidectomy is generally recommended.
- Lobectomy has lower rates of hypocalcaemia and bilateral recurrent-laryngeal-nerve risk than total thyroidectomy.
- Counsel about possible intraoperative conversion or later completion thyroidectomy if higher-risk pathology emerges.
Exam pearl: Low-risk unilateral 3-cm PTC without nodes: lobectomy is a legitimate initial option, not an obligatory total thyroidectomy.
Examiner trap: Do not mark total thyroidectomy categorically wrong for all 2–4-cm PTC; the question asks which listed operation is guideline-concordant.
Viva extension: When is total thyroidectomy favoured? Large tumours >4 cm, gross extrathyroidal extension, clinically apparent metastases or selected bilateral/high-risk features.
Q837. A 71-year-old woman previously underwent thyroidectomy for anaplastic (undifferentiated) thyroid carcinoma. She now has radiologically confirmed local recurrence, but serum thyroglobulin is not raised. Which explanation is most appropriate?
Recorded recall sessions: May 2022; January 2023; September 2024
A. Anaplastic tumour cells commonly lose follicular differentiation and thyroglobulin production
B. Normal thyroglobulin definitively excludes recurrent thyroid cancer
C. Calcitonin is universally raised in anaplastic thyroid carcinoma
D. Anti-thyroid peroxidase antibodies are a sensitive recurrence marker
Answer and explanation
A. Anaplastic tumour cells commonly lose follicular differentiation and thyroglobulin production
Anaplastic thyroid carcinoma is a highly dedifferentiated malignancy that often loses the ability to synthesise thyroglobulin or concentrate radioiodine. Therefore a normal serum thyroglobulin cannot exclude anaplastic recurrence. In contrast, thyroglobulin is an important surveillance marker in appropriately treated differentiated papillary and follicular carcinomas; calcitonin is characteristic of medullary carcinoma.
B. A normal thyroglobulin result cannot rule out a tumour that does not express or release thyroglobulin.
C. Calcitonin is associated with parafollicular C-cell-derived medullary carcinoma, not all anaplastic cancers.
D. Anti-TPO antibodies reflect autoimmune thyroid disease, not anaplastic cancer burden.
- Anaplastic carcinoma loses differentiated thyroid functions, including radioiodine uptake.
- Thyroglobulin is mainly useful after treatment of differentiated thyroid carcinoma.
- Calcitonin and CEA are markers for medullary thyroid carcinoma.
- Anaplastic thyroid cancer is aggressive and requires rapid specialist multidisciplinary evaluation.
Exam pearl: Normal thyroglobulin does not exclude anaplastic thyroid carcinoma recurrence.
Examiner trap: Do not apply differentiated-thyroid-cancer thyroglobulin surveillance rules to undifferentiated tumours.
Viva extension: Which thyroid cancers usually produce thyroglobulin? Differentiated papillary and follicular carcinomas of follicular-cell origin.
Q858. A 25-year-old woman has a thyroid nodule with amyloid stroma on cytology and markedly elevated calcitonin. Her sister previously required thyroid surgery for a similar lesion. Medullary thyroid carcinoma is confirmed. Which investigation is essential to establish whether the disease is hereditary and guide testing of relatives?
Recorded recall sessions: January 2025
A. Routine serum thyroglobulin measurement
B. Germline RET proto-oncogene testing with genetic counselling
C. BRAF V600E testing as the sole hereditary screen
D. Radioiodine uptake scanning
Answer and explanation
B. Germline RET proto-oncogene testing with genetic counselling
Medullary thyroid carcinoma arises from parafollicular C cells and may occur as part of hereditary MEN2 syndromes caused by germline RET variants. All patients with MTC should be offered germline RET testing, including apparently sporadic cases, with cascade counselling/testing for relatives when a pathogenic variant is found. Calcitonin and CEA are tumour markers, not substitutes for germline testing.
A. Thyroglobulin is a follicular-cell marker and does not establish inherited MTC.
C. BRAF mutations are more associated with papillary thyroid carcinoma; they do not replace germline RET testing for MTC.
D. Medullary carcinoma generally does not concentrate radioiodine, and scintigraphy does not determine hereditary status.
- MTC arises from C cells and often produces calcitonin.
- Hereditary MTC is linked to germline RET mutations and MEN2.
- All patients with MTC should be offered germline RET testing.
- If RET-positive, offer genetic counselling and appropriate testing of first-degree relatives.
Exam pearl: Confirmed MTC → offer germline RET testing, even without a family history.
Examiner trap: The source diagnosis is already covered elsewhere in the bank; this question instead tests hereditary risk assessment and cascade screening.
Viva extension: What additional tumour should be excluded before thyroid surgery in MEN2? Phaeochromocytoma, using appropriate biochemical testing.
Q870. A 38-year-old woman has a 1.8-cm thyroid nodule without suspicious lymphadenopathy. Ultrasound-guided FNA reports Bethesda III (atypia of undetermined significance), and she has no compressive symptoms. Which is a reasonable next diagnostic step?
Recorded recall sessions: 2021 (session not specified)
A. Immediate radioiodine ablation without a tissue diagnosis
B. Treat with levothyroxine suppression as proof of benignity
C. Ignore the result permanently because Bethesda III is benign
D. Repeat ultrasound-guided FNA with risk-stratified reassessment and consider molecular testing where available
Answer and explanation
D. Repeat ultrasound-guided FNA with risk-stratified reassessment and consider molecular testing where available
Bethesda III is an indeterminate cytological category, not a definitive benign or malignant diagnosis. Repeat ultrasound-guided FNA is a guideline-supported next step; sonographic risk, repeat cytology, patient preference and availability of molecular testing guide observation versus diagnostic surgery. Radioiodine is not a diagnostic substitute.
A. Radioiodine does not establish a histological diagnosis and is not routine initial treatment for an indeterminate nodule.
B. TSH-suppressive levothyroxine does not resolve the indeterminate cytology and has adverse effects.
C. Bethesda III has a nonzero malignancy risk and requires an individualised plan.
- Bethesda III = atypia of undetermined significance/follicular lesion of undetermined significance.
- Repeat FNA is often the next diagnostic step.
- Persistent indeterminate cytology may lead to molecular testing, surveillance or diagnostic lobectomy.
- High-risk ultrasound features and clinical context modify management.
Exam pearl: Bethesda III is indeterminate: repeat FNA and risk-stratify.
Examiner trap: Do not confuse Bethesda III with Bethesda II benign cytology or Bethesda VI malignant cytology.
Viva extension: Why cannot cytology alone prove follicular carcinoma? Capsular or vascular invasion requires histological assessment.
Q878. Following total thyroidectomy for medullary thyroid carcinoma, serial calcitonin values obtained with the same assay show a doubling time of five months. What does this most strongly suggest?
Recorded recall sessions: January 2021; January 2023
A. Reliable biochemical cure
B. Rapid biochemical progression and a less favourable prognosis
C. Differentiated papillary thyroid carcinoma recurrence
D. Normal physiological postoperative calcitonin recovery
Answer and explanation
B. Rapid biochemical progression and a less favourable prognosis
Calcitonin is a tumour marker secreted by medullary thyroid carcinoma C cells. Serial calcitonin and CEA doubling times are useful measures of tumour kinetics; a calcitonin doubling time shorter than six months is associated with more aggressive disease than a doubling time exceeding two years. Imaging and treatment depend on the complete clinical picture.
A. A rapidly rising marker is incompatible with biochemical cure after complete resection.
C. Thyroglobulin, rather than calcitonin kinetics, is the principal differentiated-thyroid tumour marker.
D. Persistent rapid doubling of calcitonin is not a routine physiological postoperative pattern.
- Use serial results from the same laboratory/assay.
- Calcitonin and CEA doubling times complement structural imaging.
- A short doubling time indicates poorer prognosis but is not by itself an indication for a specific operation.
- MTC arises from parafollicular C cells and is not treated with radioiodine.
Exam pearl: MTC prognosis is influenced by calcitonin doubling time, not TSH suppression.
Examiner trap: Do not interpret a single elevated calcitonin value as a doubling time.
Viva extension: What other serum marker is followed in MTC? Carcinoembryonic antigen (CEA); its trend can provide additional prognostic information.
Q914. A 29-year-old has a 2-cm thyroid nodule on ultrasound. Serum TSH is markedly suppressed and free T4 is mildly raised. Before deciding on cytology, which test best establishes whether the nodule is autonomously functioning?
Recorded recall sessions: April 2021
A. Serum thyroglobulin measurement
B. Thyroid radionuclide scintigraphy
C. Routine open thyroid biopsy
D. Serum calcitonin alone
Answer and explanation
B. Thyroid radionuclide scintigraphy
When TSH is suppressed in a patient with a thyroid nodule, radionuclide scintigraphy can identify a hyperfunctioning (“hot”) nodule. Such nodules have a low malignancy probability and are usually not sampled by FNA solely because of size; clinical and ultrasound red flags still require individual assessment. Ultrasound and biochemical assessment remain essential components of the initial work-up.
A. Thyroglobulin is nonspecific in an intact thyroid and does not determine functional autonomy.
C. Open biopsy is not the first-line method for evaluating a thyroid nodule.
D. Calcitonin can be useful in selected circumstances but does not show iodine uptake or autonomy.
- Measure TSH and perform high-quality thyroid ultrasound in initial nodule assessment.
- Low TSH raises the possibility of an autonomously functioning nodule.
- Scintigraphy differentiates hyperfunctioning from nonfunctioning tissue.
- FNA thresholds depend on ultrasound risk, size and clinical context.
Exam pearl: Suppressed TSH + nodule → consider scintigraphy before FNA.
Examiner trap: Do not order radionuclide scans routinely for every euthyroid nodule.
Viva extension: Why are hot nodules often not biopsied? Their malignancy probability is low; management focuses on autonomous hormone production unless other suspicious features exist.
Q915. A 62-year-old with longstanding Hashimoto thyroiditis develops rapidly enlarging thyroid swelling. Core biopsy demonstrates diffuse large B-cell lymphoma expressing CD20. Staging shows no immediate airway threat. Which treatment principle is most appropriate?
Recorded recall sessions: May 2023
A. Routine total thyroidectomy as definitive first-line therapy
B. Radioiodine ablation of the thyroid
C. Systemic immunochemotherapy guided by lymphoma staging
D. Levothyroxine alone until spontaneous resolution
Answer and explanation
C. Systemic immunochemotherapy guided by lymphoma staging
Primary thyroid diffuse large B-cell lymphoma is generally treated as a systemic B-cell lymphoma with rituximab-containing immunochemotherapy, with radiotherapy considered according to stage and multidisciplinary planning. Thyroidectomy is not the routine definitive treatment and may add morbidity; urgent airway intervention is reserved for clinically significant obstruction. CD20 positivity provides the target for rituximab.
A. Extensive thyroid resection is usually unnecessary once a tissue diagnosis of lymphoma is established.
B. Radioiodine treats iodine-avid differentiated thyroid disease or autonomous tissue, not DLBCL.
D. Thyroid hormone replacement treats associated hypothyroidism, not the lymphoma.
- Rapid enlargement on a Hashimoto background raises suspicion for thyroid lymphoma.
- Core tissue and immunophenotyping are often required for diagnosis.
- CD20 expression supports anti-CD20 therapy.
- Airway compromise requires immediate multidisciplinary assessment.
Exam pearl: CD20-positive thyroid DLBCL → lymphoma-directed systemic treatment, not routine thyroidectomy.
Examiner trap: Do not mistake a rapidly growing thyroid lymphoma for anaplastic thyroid carcinoma without adequate tissue.
Viva extension: Which monoclonal antibody targets CD20? Rituximab; treatment is individualized by haematology and lymphoma staging.
Q948. A 45-year-old woman has a firm irregular thyroid mass, suspicious ipsilateral cervical nodes and persistent new hoarseness. Before definitive thyroid surgery, which investigation is particularly important to establish baseline laryngeal nerve function?
Recorded recall sessions: September 2020
A. Flexible nasolaryngoscopy to assess vocal-fold movement
B. Serum thyroglobulin alone
C. Routine barium swallow instead of laryngeal examination
D. Empirical levothyroxine suppression before examining the vocal cords
Answer and explanation
A. Flexible nasolaryngoscopy to assess vocal-fold movement
Preoperative dysphonia in suspected thyroid cancer mandates laryngeal examination to document vocal-fold mobility and possible recurrent laryngeal nerve involvement. Identifying pre-existing paralysis changes surgical planning and is essential when considering risk to the contralateral nerve.
B. Thyroglobulin does not establish vocal-cord function and is not a substitute for diagnostic work-up.
C. A barium study does not evaluate recurrent laryngeal nerve motor function.
D. Empirical hormone suppression neither investigates hoarseness nor assesses invasive malignancy.
- All thyroid surgery patients require documented preoperative voice assessment.
- Dysphonia, prior neck surgery or extensive posterior tumour invasion are indications for laryngoscopy.
- Preoperative vocal-fold paralysis raises concern for locally invasive thyroid malignancy.
- An occult contralateral injury may create a dangerous bilateral vocal-fold palsy.
Exam pearl: Hoarseness before thyroidectomy → inspect the vocal folds before operating.
Examiner trap: Do not assume that a patient with thyroid cancer has a normal recurrent laryngeal nerve simply because the voice sounds near normal.
Viva extension: Why does preoperative unilateral vocal-fold paralysis matter? It can indicate tumour invasion and increases the consequence of injury to the remaining functioning nerve.
Q974. A 32-year-old has a 2-cm intrathyroidal papillary thyroid carcinoma confined to one lobe. Neck ultrasound shows no suspicious central or lateral nodes, and there is no gross extrathyroidal extension. She is undergoing a thyroid lobectomy. What is the recommended approach to clinically uninvolved central neck lymph nodes?
Recorded recall sessions: September 2019
A. Perform bilateral central-compartment dissection in every papillary thyroid cancer
B. Perform prophylactic lateral neck dissection regardless of nodal imaging
C. Abandon lobectomy and give radioactive iodine as the only initial treatment
D. Do not routinely perform prophylactic central-compartment neck dissection
Answer and explanation
D. Do not routinely perform prophylactic central-compartment neck dissection
Current ATA guidance discourages prophylactic central-compartment lymph node dissection for most small, non-invasive cT1–T2, cN0 papillary thyroid carcinomas. Therapeutic compartment dissection is indicated when nodes are structurally involved; unnecessary prophylactic surgery adds morbidity.
A. Routine prophylactic dissection adds recurrent laryngeal nerve and hypoparathyroidism risk without proven benefit in most small non-invasive cN0 tumours.
B. Lateral neck dissection is therapeutic for clinically involved disease, not routine in a cN0 low-risk patient.
C. RAI is not a replacement for indicated surgical treatment of this resectable low-risk lesion.
- Low-risk unilateral PTC up to 2 cm may be treated with lobectomy.
- Clinically node-negative T1–T2 PTC usually needs no prophylactic central neck dissection.
- Known structural central nodal disease warrants therapeutic compartment dissection.
- Recurrent laryngeal nerve injury and hypoparathyroidism are important central-neck surgical risks.
Exam pearl: Small non-invasive cN0 papillary thyroid cancer: no routine prophylactic central neck clearance.
Examiner trap: Do not confuse therapeutic dissection of known involved nodes with prophylactic clearance of normal nodes.
Viva extension: Which nodal compartments form the central neck? Level VI, with level VII included in relevant modern surgical guidance.
Q977. A 46-year-old woman has a suspicious thyroid nodule. TSH and free T4 are normal, but basal calcitonin is markedly elevated at 2,000 ng/L. Which diagnosis best explains this laboratory pattern?
Recorded recall sessions: January 2021
A. Papillary thyroid carcinoma with isolated thyroglobulin production.
B. Graves hyperthyroidism.
C. Medullary thyroid carcinoma arising from parafollicular C cells.
D. Primary hypothyroidism due to Hashimoto thyroiditis.
Answer and explanation
C. Medullary thyroid carcinoma arising from parafollicular C cells.
Medullary thyroid carcinoma is a neuroendocrine malignancy of calcitonin-secreting parafollicular cells. Thyroid follicular function may remain normal, so a normal TSH and free T4 do not exclude it; marked calcitonin elevation is a major clue requiring specialist assessment.
A. Papillary cancer derives from follicular cells and is not characteristically a calcitonin-secreting tumour.
B. Graves disease typically shows suppressed TSH and raised thyroid hormones, not isolated massive calcitonin elevation.
D. Primary hypothyroidism usually raises TSH and lowers free T4 and does not explain marked calcitonin secretion.
- CEA is another useful MTC marker.
- Germline RET testing is indicated for patients with confirmed MTC.
- Screen for phaeochromocytoma before surgery in hereditary MTC/MEN2.
- Calcitonin may rise with some non-MTC conditions; interpret magnitude and context.
Exam pearl: Very high calcitonin with a thyroid nodule points toward MTC even if thyroid hormones are normal.
Examiner trap: Do not confuse calcitonin with thyroglobulin, the usual marker for differentiated thyroid cancer.
Viva extension: What hereditary syndrome is associated? MEN2, caused by pathogenic germline RET variants.
Q998. A 35-year-old woman has a newly detected 2-cm palpable thyroid nodule without compressive symptoms or palpable lymphadenopathy. Which imaging test should be performed first to characterise the nodule and survey cervical lymph nodes?
Recorded recall sessions: April 2021
A. CT neck with intravenous contrast
B. Ultrasound of the thyroid and cervical lymph nodes
C. Radioiodine whole-body scintigraphy regardless of TSH
D. PET-CT for all palpable thyroid nodules
Answer and explanation
B. Ultrasound of the thyroid and cervical lymph nodes
High-resolution neck ultrasound is the initial imaging investigation for a clinically detected thyroid nodule. It characterises size, echogenicity, margins, microcalcifications and cervical nodes, informing risk stratification and whether ultrasound-guided FNAC is needed. Serum TSH should also be measured; scintigraphy is considered when TSH is low.
A. CT is reserved for selected large, substernal, invasive or otherwise complex disease and is not routine first-line imaging.
C. Radionuclide scanning is not routinely appropriate when TSH is normal or high.
D. PET-CT is not an initial investigation for an uncomplicated thyroid nodule.
- Initial work-up includes serum TSH and high-resolution thyroid/cervical ultrasound.
- Ultrasound risk features guide FNAC decisions according to nodule size and local guidance.
- A suppressed TSH can prompt radionuclide scintigraphy for an autonomous nodule.
- Suspicious cervical nodes require targeted evaluation, often with ultrasound-guided sampling.
Exam pearl: New thyroid nodule: measure TSH and obtain high-resolution neck ultrasound.
Examiner trap: Do not send every thyroid nodule directly for FNAC without sonographic and biochemical assessment.
Viva extension: When is scintigraphy useful? In a nodule with low TSH to assess functional autonomy; a hyperfunctioning nodule is rarely malignant.
Q1005. A 30-year-old woman has a newly discovered thyroid nodule. Ultrasound and cytology prompt specialist assessment for thyroid malignancy, but no specific subtype has yet been established. Among the following primary thyroid cancers, which is the most common histological type overall?
Recorded recall sessions: January 2025
A. Medullary thyroid carcinoma
B. Anaplastic thyroid carcinoma
C. Follicular thyroid carcinoma
D. Papillary thyroid carcinoma
Answer and explanation
D. Papillary thyroid carcinoma
Papillary thyroid carcinoma is the predominant primary thyroid malignancy, accounting for roughly 70–80% of thyroid cancer diagnoses in many series. It often arises in younger adults, commonly spreads through lymphatics to cervical nodes and frequently has a favourable prognosis. However, prevalence alone does not diagnose the particular nodule: ultrasound risk assessment and cytopathology are essential.
A. Medullary carcinoma arises from parafollicular C cells and is much less common; calcitonin secretion and RET/MEN2 associations are important clues.
B. Anaplastic carcinoma is rare, highly aggressive and usually presents in older adults with a rapidly growing invasive mass.
C. Follicular carcinoma is less common than papillary and tends to spread haematogenously rather than primarily by lymphatics.
- Papillary and follicular cancers arise from thyroid follicular cells and are classed as differentiated carcinomas.
- Papillary thyroid carcinoma classically shows nuclear clearing, grooves and pseudoinclusions, but frequency is a separate concept from histological identification.
- Follicular carcinoma requires capsular and/or vascular invasion for histological diagnosis.
- A thyroid nodule cannot be labelled malignant, or assigned subtype, on age or population frequency alone.
Exam pearl: When an MRCS question explicitly asks the most prevalent thyroid carcinoma overall, choose papillary.
Examiner trap: Do not turn an epidemiological answer into a diagnosis for an individual 30-year-old with an uncharacterised nodule.
Viva extension: How does typical metastatic spread differ between papillary and follicular carcinoma? Papillary frequently spreads to cervical lymph nodes; follicular carcinoma more commonly spreads via blood to lung and bone.
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