Glomerulonephritis: role of retinol-binding protein in monitoring and prognostication

Retinol-binding protein (RBP), traditionally regarded as a marker of proximal tubular dysfunction, has recently gained attention for its potential relevance in chronic kidney disease (CKD). Membranous glomerulonephritis (MGN) is a leading cause of nephrotic syndrome in adults and an important contributor to CKD progression toward end-stage renal disease (ESRD). Therefore, effective monitoring of patients with MGN, particularly those at risk of deterioration, is essential for timely intervention. This study aimed to evaluate the use of urinary RBP as a non-invasive biomarker for monitoring and prognostication in patients with primary and secondary MGN using the Enzyme-linked Immunosorbent Assay (ELISA) method. A total of 125 patients (81 with primary MGN and 44 with secondary MGN) were diagnosed at Hospital Serdang and Hospital Kuala Lumpur between January 2012 and October 2019. Of these, 69 patients (45 primary and 24 secondary MGN) consented to participate. Urinary RBP was detected in 27 of 45 primary MGN patients (60.0%) and 6 of 24 secondary MGN patients (25.0%). Urinary RBP showed significant negative correlations (r= -0.734) with estimated glomerular filtration rate, indicating worsening renal impairment. Logistic regression further demonstrated that urinary RBP is a significant prognostic indicator in primary MGN. These findings suggest that urinary RBP may serve as a useful, non-invasive biomarker for monitoring disease progression and prognostication in patients with primary MGN, potentially improving clinical decision-making compared to traditional monitoring methods.