A 30-year-old woman has persistent microscopic hematuria detected on routine urinalysis. Blood pressure and serum creatinine are normal and there is no proteinuria. Her father had lifelong 'benign' hematuria. Renal biopsy electron microscopy shows uniform diffuse thinning of the glomerular basement membrane with no splitting and no deposits; immunofluorescence is negative. What is the diagnosis?

• A Alport syndrome
• B Post-infectious glomerulonephritis, resolving phase
• C IgA nephropathy
• D Thin basement membrane lesion (benign familial hematuria) ✓

Explanation

Thin basement membrane lesion results from heterozygous mutations in COL4A3 or COL4A4 and produces isolated hematuria with a uniformly thinned GBM, preserved renal function, and an excellent long-term prognosis. Alport syndrome, the key distractor, is caused by heterozygous carrier state versus X-linked or autosomal recessive COL4A5 or COL4A3/COL4A4 mutations and shows GBM thickening, splitting and basket-weave lamellation with progression to deafness and renal failure.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.