Thin Basement Membrane Disease (TBMD)

Thin Basement Membrane Disease (TBMD) is a genetic kidney disorder characterized by thinning of the glomerular basement membrane, leading to persistent microscopic hematuria. It is commonly inherited in an autosomal dominant pattern and is considered a benign condition compared to other hereditary kidney diseases.

Causes and Genetics

TBMD is typically caused by mutations in type IV collagen genes, including COL4A3 and COL4A4. These mutations affect the structural integrity of the glomerular basement membrane (GBM), resulting in increased permeability.

Clinical Features

• Persistent microscopic hematuria
• Occasional episodes of macroscopic hematuria
• Normal renal function in most cases
• Absence of proteinuria or progressive renal disease

Diagnosis

Diagnosis is primarily established through urinalysis, family history, and electron microscopy, which reveals thinning of the GBM (<250 nm in thickness). Genetic testing may be performed for confirmation in cases with atypical features.

Management and Prognosis

TBMD is generally a benign condition with a favorable prognosis. Management focuses on regular monitoring of renal function and blood pressure. Patients are advised to avoid nephrotoxic medications and maintain a healthy lifestyle.