Clinical value of repeat kidney biopsy in pediatric IgA vasculitis nephritis

For pediatric patients with IgA vasculitis nephritis (IgAVN), therapeutic decisions during relapse are often guided by empirical adjustments based on clinical manifestations, lacking timely pathological evidence. We aimed to investigate the dynamic evolution of kidney pathology in children with IgAVN and evaluate the clinical utility of repeat kidney biopsy in treatment decisions.

Retrospective analysis was conducted on 30 children with IgAVN who underwent repeat kidney biopsy. We summarized demographic characteristics, clinical relapse features, and indications for repeat kidney biopsy. Clinical indicators and kidney pathological changes were compared from initial to repeat kidney biopsy, and correlation between clinical indicators and pathological progression was analyzed. Longitudinal progression after treatment adjustments based on repeat kidney biopsy findings was assessed using linear mixed-effects model (LMM).

Median interval between the two kidney biopsies was 39.95 months. During this period, despite no significant changes in 24-h urinary protein (24 h UTP) and urinary red blood cell (URBC) levels, estimated glomerular filtration rate (eGFR) showed a slight increasing trend (141.68 vs. 167.37 mL/min/1.73 m², P = 0.031). In contrast, pathological findings revealed significant deterioration of ISKDC grades (P < 0.001), with proportion of grade IIIb lesions rising from 26.67% at initial biopsy to 50.00% at repeat biopsy. Concurrently, incidence of chronicity indicators, including global glomerulosclerosis, tubular atrophy, and interstitial fibrosis, significantly increased (all P < 0.05). Fluctuations in 24 h UTP and URBC failed to sensitively reflect deterioration of intrarenal activity (all P > 0.05); only fluctuations in eGFR correlated with global sclerosis progression (P = 0.019). Consequently, 80.00% of children had treatment regimen adjustment based on repeat biopsy results. Following adjustments, both 24 h UTP (P < 0.001) and URBC (P < 0.001) decreased significantly, while serum creatinine (SCr) levels remained stable (P = 0.109), indicating a positive therapeutic response.

A distinct dissociation exists between clinical presentation and kidney pathological progression during relapse in children with IgAVN. Repeat kidney biopsy is particularly beneficial for pediatric patients with clinical relapse whose conditions cannot be accurately assessed by conventional indicators; it facilitates enhanced treatment precision and improves long-term kidney outcomes.