A patient with ileal resection presents with fat malabsorption and steatorrhea. You suspect disruption of the enterohepatic circulation of bile acids.
Which of the following statements regarding bile acids is correct?
Decoding the Stem
Explanation
A. Conjugation: ✅ Correct. Bile acids are synthesized from cholesterol in the liver and are conjugated with glycine (most common) or taurine. This increases their solubility and prevents passive reabsorption in the proximal small intestine, ensuring high concentrations for fat emulsification.
B. 50% reabsorbed: ❌ Incorrect. Approximately 95% of bile acids are reabsorbed from the intestinal lumen via the enterohepatic circulation, mainly in the terminal ileum.
C. Formed in distal ileum: ❌ Incorrect. Bile acids are synthesized in the liver. The distal ileum is the primary site of their reabsorption.
D. 10 mg/day synthesis: ❌ Incorrect. The liver synthesizes approximately 200–600 mg/day to replace the small amount lost in feces.
E. Bacterial Metabolism: ❌ Incorrect. Gut bacteria actively metabolize primary bile acids (cholic, chenodeoxycholic) into secondary bile acids (deoxycholic, lithocholic).
🧠Clinical Pearls
| Key Concept | Fact |
|---|---|
| Synthesis Site | Liver (from cholesterol) |
| Primary Site of Reabsorption | Terminal Ileum (~95% efficiency) |
| Metabolism | Bacteria convert Primary to Secondary |
Integrated Clinical Questions
1. What happens after ileal resection regarding bile acid physiology?
2. Name the two primary bile acids.
3. Name the two secondary bile acids formed by gut bacteria.
4. What is the main function of bile acids in the intestine?
5. Which vitamins are poorly absorbed when bile acid concentration is low?
⚡ Exam Pearls
- Conjugation is the key step before secretion to maintain solubility.
- 95% is the magic number for reabsorption efficiency.
- Terminal Ileum is the specific anatomical site of reabsorption.
- Gut bacteria modification is a frequent exam topic.
0 Comments