- Clinical science
Thin basement membrane nephropathy
Summary
Thin basement membrane nephropathy is a primary glomerulonephritis caused by abnormalities of type IV collagen and thinning of the glomerular basement membrane. Patients typically present with episodes of intermittent gross hematuria and flank pain, often triggered by upper respiratory tract (URT) infections or exercise. Urinalysis shows persistent microhematuria and sometimes proteinuria. Kidney biopsy is required for diagnosis, showing diffuse thinning of the glomerular basement membrane. While the disease generally has an excellent prognosis and often does not require treatment, patients with proteinuria should be treated with ACE inhibitors to slow progression.
Epidemiology
- Prevalence: 5–9%
Epidemiological data refers to the US, unless otherwise specified.
Etiology
- Hereditary (usually autosomal dominant) or sporadic
Pathophysiology
- Abnormalities of type IV collagen cause thinning of the glomerular basement membrane → transient ruptures of glomerular capillary wall → hematuria
Clinical features
- Usually asymptomatic
- Episodic gross hematuria, possibly in combination with flank pain may occur, typically following an upper respiratory tract infection or exercise.
- Other symptoms of nephritic syndrome (e.g., hypertension) can occur (especially in adults).
- Very rarely progresses to end-stage renal disease
Diagnostics
Diagnosis is usually assumed in patients based on the presentatation and a family history of benign hematuria. Renal biopsy is reserved for cases in which signs of progression (e.g., proteinuria, hyperkalemia) occur or if the family history is unclear.
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Urinalysis
- Usually only persistent microhematuria
- Possible episodic gross hematuria, potentially associated with hypercalciuria and hyperuricosuria
- Minor proteinuria is possible, especially in adults
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Renal biopsy
- Light microscopy: no abnormalities
- Electron microscopy: diffuse thinning of the glomerular basement membrane
Treatment
- Isolated hematuria does not require treatment.
- ACE inhibitors/AT-II antagonists in patients with proteinuria > 500–1000 mg/day
