Thin-basement-membrane nephropathy in adults with persistent hematuria

Area of Science:

• Nephrology
• Pathology
• Genetics

Background:

• Thin-basement-membrane nephropathy (TBMN) is characterized by diffuse thinning of the glomerular basement membrane (GBM).
• TBMN is often associated with hematuria, presenting as benign recurrent hematuria.
• The exact incidence of TBMN in patients with idiopathic hematuria requires further investigation.

Purpose of the Study:

• To determine the incidence of TBMN among adult patients presenting with idiopathic hematuria.
• To compare the prevalence of TBMN with other glomerulonephropathies, such as IgA nephropathy.
• To evaluate the diagnostic utility of GBM thickness measurement in patients with persistent hematuria.

Main Methods:

• A prospective study involving 80 adult patients with idiopathic hematuria (macroscopic or microscopic) without azotemia.
• Renal biopsies were performed, analyzed by light microscopy, and further evaluated by electron microscopy for GBM morphometry.
• Patients were followed for a median of 50 months to assess hematuria resolution and disease progression.

Main Results:

• Thin-basement-membrane nephropathy (TBMN) was diagnosed in 18 of 42 patients with initially normal light microscopy findings.
• The mean GBM thickness in TBMN patients was significantly reduced (191 nm) compared to normal controls (350 nm).
• TBMN was identified in 31% of patients with persistent microscopic hematuria, a prevalence similar to idiopathic IgA nephropathy (27/80 patients).

Conclusions:

• Thin-basement-membrane nephropathy is a common cause of persistent microscopic hematuria in adults, with an incidence comparable to idiopathic IgA nephropathy.
• Electron microscopic morphometric analysis of GBM thickness is essential for diagnosing TBMN in adults with unexplained hematuria.
• Diagnosis of TBMN can guide patient management and counseling regarding prognosis and potential complications.