Clinicopathological Spectrum of Pediatric Renal Biopsies: A Retrospective Observational Study From South India

Kidney disorders in Indian children remain incompletely characterized, with impaired renal function affecting a notable proportion of the pediatric population. Renal biopsy remains underutilized, as childhood nephrotic syndrome is often presumed to reflect minimal change disease (MCD), and no national pediatric renal biopsy registry exists. This study addresses this gap by examining the indications for renal biopsy and the histopathological patterns observed in a South Indian cohort. The study aimed to determine the epidemiological profile, clinical indications, and histopathological spectrum of pediatric renal biopsies and to assess their correlation with selected clinical and laboratory parameters.

This retrospective observational study, conducted from January 2023 to February 2026, included children aged ≤18 years who underwent native renal biopsy at a tertiary care center. Clinical and laboratory data, including hemoglobin, serum creatinine, serum C3 and C4 levels, urine protein-to-creatinine ratio, and urinalysis findings, were retrieved from case records and the laboratory information system. Ultrasound-guided renal biopsies were performed using 16- or 18-gauge needles, with two cores obtained for light microscopy and immunofluorescence. Immunofluorescence staining was performed for IgG, IgA, IgM, C3, C1q, kappa, and lambda, and the results were evaluated by a nephropathologist. Inadequate biopsy specimens containing fewer than seven glomeruli were excluded.

Among the 54 pediatric renal biopsies, 66.7% were from female patients (M/F ratio, 1:2), and the mean age was 10.77 ± 4.54 years. Nephrotic syndrome was the leading indication for biopsy (50%, n = 27), followed by nephritic syndrome (24.07%, n = 13). Secondary glomerulonephritis (GN) predominated (57.41%), with lupus nephritis (LN) being the most frequent diagnosis (37%, n = 20), followed by infection-related GN (IRGN) (16.7%, n = 9) and MCD/focal segmental glomerulosclerosis (13% each, n = 7). Among patients with LN, Class IV was the predominant class (50%, n = 10), followed by Class II (30%, n = 6). Serum C3 and C4 levels differed significantly across diagnostic categories (both p < 0.001), with consistently low levels observed in patients with LN and IRGN.

Nephrotic syndrome remains the leading indication for pediatric renal biopsy, with secondary GN, particularly LN and IRGN, predominating in this cohort, in contrast to patterns reported in Western studies. LN was the most frequent histopathological diagnosis, with Class IV LN accounting for half of the LN cases. Complement levels varied significantly across diagnostic categories, with low C3 and C4 levels observed in LN, consistent with immune complex-mediated complement consumption. These findings reinforce the importance of renal biopsy in establishing accurate diagnoses and guiding the management of pediatric renal diseases.