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Thin Basement Membrane Disease — RACP Adult Medicine MCQ

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ModerateNephrologyThin Basement Membrane DiseaseRACP Adult Medicine

A 20-year-old woman has persistent microscopic haematuria (dysmorphic RBCs) found on routine urinalysis. She has no proteinuria, normal renal function, and normal blood pressure. Family history reveals her mother and maternal aunt also have persistent microscopic haematuria with normal renal function. Complement levels are normal. What is the most likely diagnosis?

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Correct answer: E — Thin basement membrane disease

Persistent isolated microscopic haematuria (dysmorphic = glomerular) with no proteinuria, normal renal function, and autosomal dominant family history of haematuria with benign outcomes is thin basement membrane disease (thin GBM nephropathy). It is a collagen IV mutation causing thinning of the GBM. Prognosis is excellent (benign familial haematuria). Must be distinguished from early Alport syndrome (X-linked, progressive renal failure, deafness — needs genetic testing to differentiate).

Reference: KDIGO – 2021 – GN; KHA 2024