IgA nephropathy (Berger Disease)
IgA nephropathy is the most common primary glomerulonephritis worldwide and is characterized by IgA immune-complex deposition in the glomerular mesangium, leading to inflammation and hematuria.
1. Pathogenesis
Key mechanism:
- Formation of abnormally glycosylated IgA1 molecules.
- These IgA molecules trigger formation of autoantibodies against IgA1.
- The resulting immune complexes deposit in the glomerular mesangium.
Result:
- Mesangial proliferation
- Complement activation (alternative pathway)
- Glomerular inflammation
2. Clinical Features
Typical presentation:
Recurrent episodic hematuria
Classically occurs 1–2 days after upper respiratory infection.
Common findings:
- Gross hematuria (“cola-colored urine”)
- Microscopic hematuria
- Mild proteinuria
- Sometimes hypertension
- Rarely nephrotic syndrome
A classic exam clue:
Synpharyngitic hematuria
Hematuria occurs during the infection, not weeks later.
3. Histopathology
Light Microscopy
- Mesangial proliferation
- Expansion of mesangial matrix
Immunofluorescence
- Granular IgA deposition in mesangium (diagnostic)
Electron Microscopy
- Electron-dense deposits in mesangium
4. Important Associations
IgA nephropathy may occur with:
- Henoch-Schönlein purpura (IgA vasculitis)
- Chronic liver disease
- Celiac disease
- Respiratory or GI infections
Henoch-Schönlein purpura is essentially the systemic form of IgA nephropathy.
5. Prognosis
Course is variable.
Possible outcomes:
- Complete remission
- Slowly progressive CKD
- End-stage renal disease (about 20–40% over 20 years)
Poor prognostic factors:
- Persistent heavy proteinuria
- Hypertension
- Reduced GFR at diagnosis
6. Treatment
Supportive
- ACE inhibitors / ARBs → reduce proteinuria
- Blood pressure control
Moderate disease
- Corticosteroids
Severe disease
- Immunosuppressive therapy
📝 High-Yield Exam Points
- Most common primary glomerulonephritis worldwide
- Hematuria within 1–2 days after URI
- IgA deposition in mesangium
- Associated with Henoch-Schönlein purpura
- Mesangial immune complex deposition
❓ High-Yield Quiz
1. What is the most common primary glomerulonephritis worldwide?
Answer: IgA Nephropathy (Berger Disease)
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2. When does hematuria typically occur relative to a respiratory infection?
Answer: 1–2 days (Synpharyngitic)
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3. Where are the immune complexes primarily deposited in the glomerulus?
Answer: The Mesangium
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4. What is the underlying biochemical defect in IgA1 molecules?
Answer: Abnormal glycosylation (Galactose-deficient IgA1)
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5. Which systemic vasculitis is closely associated with IgA Nephropathy?
Answer: Henoch-Schönlein purpura (IgA vasculitis)
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6. What is the characteristic diagnostic finding on Immunofluorescence?
Answer: Granular IgA deposits in the mesangium
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7. Which complement pathway is primarily activated in this disease?
Answer: Alternative pathway
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8. What medications are used first-line to reduce proteinuria and protect kidneys?
Answer: ACE inhibitors or ARBs
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9. What color is the urine classically described as during gross hematuria?
Answer: Cola-colored or tea-colored
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10. Name a gastrointestinal association of IgA Nephropathy.
Answer: Celiac disease (or chronic liver disease)
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