Characterization of urinary protein excretion patterns and their diagnostic significance in various types of primary glomerulonephritis

Abstract

What distinguishes one form of glomerular injury from another at the molecular level? This research examined urinary protein excretion patterns across five subtypes of primary glomerulonephritis to identify characteristic profiles with diagnostic utility. A prospective cohort of 198 biopsy-confirmed patients underwent comprehensive proteomic analysis of 24-hour urine collections between March 2022 and September 2024. Quantification of albumin, immunoglobulin G, transferrin, beta-2-microglobulin, and alpha-1-microglobulin was performed using nephelometric and enzyme immunoassay techniques. Membranous glomerulonephritis demonstrated the highest albumin excretion (mean 3256 mg/24h, SD 847), while focal segmental glomerulosclerosis showed elevated tubular markers suggesting concurrent tubulointerstitial involvement. Minimal change disease exhibited predominantly selective proteinuria with albumin-to-IgG ratios exceeding 8.2. IgA nephropathy patients displayed intermediate patterns with moderate mixed proteinuria. The selectivity index proved valuable for differentiating minimal change from focal segmental glomerulosclerosis, achieving sensitivity of 87.3% and specificity of 91.6%. These findings support integration of urinary protein profiling into diagnostic algorithms for glomerular diseases, potentially reducing reliance on invasive biopsy procedures in selected clinical scenarios.