Thin Basement Membrane Nephropathy

Thin basement membrane nephropathy (TBMN), also known as thin basement membrane disease, is one of the most prevalent yet underrecognized causes of glomerular bleeding in both children and adults. TBMN is a genetic and often familial disorder caused by mutations in the genes encoding various chains of type IV collagen, which is the primary component of the glomerular basement membrane (GBM). TBMN was previously known as benign familial hematuria, but this term is no longer favored due to an improved understanding of the genetic etiologies and variations in the clinical presentation of the condition. Other previously used nomenclature no longer favored include "benign familial hematuria," "benign persistent hematuria," and "benign essential hematuria."  TBMN is characterized by diffuse thinning of the GBM on renal biopsy and clinically presents as isolated microscopic hematuria in most cases. However, other findings, such as proteinuria, hypertension, and varying degrees of kidney function impairment, may also be present. TBMN shares overlapping features with Alport syndrome, as both conditions are caused by mutations in type IV collagen genes. However, unlike Alport syndrome, particularly its most common X-linked variant, TBMN does not have extrarenal features. Please see StatPearls' companion resource, "Alport Syndrome," for further information.