Repeat kidney biopsy in pediatric lupus nephritis: an analysis of associated clinical-pathological features and outcomes

Background The utility of repeat kidney biopsy in pediatric lupus nephritis (LN) remains debated. This study aims to evaluate pathological evolution, therapeutic implications, and prognostic impact of repeat biopsies in children with LN. Methods We conducted a retrospective analysis of 19 pediatric LN patients (aged 5–18 years) who underwent ≥2 kidney biopsies at Nanjing Children's Hospital (2009–2022). Pathological classification (ISN/RPS criteria), activity/chronicity indices, and treatment responses were compared between biopsies. Statistical analyses were performed using SPSS 21.0, with P < 0.05 considered significant. Results The primary indication for repeat biopsy was proteinuria recurrence (73.7%, 14/19). Pathological class transformation occurred in 47.4% (9/19) of cases (e.g., class III to IV), with a higher proportion of non-nephrotic type presentation in the transformation group (77.8% vs. 20.0%, P < 0.05). Treatment regimens were adjusted in 63.2% (12/19) of patients post-biopsy (e.g., cyclophosphamide to mycophenolate mofetil). Although chronicity scores increased significantly (e.g., glomerulosclerosis: 57.9% to 89.5%, P < 0.05), short-term kidney remission rates did not differ between groups with and without pathological transformation (77.8% vs. 80.0%, P > 0.05). Conclusion Repeat kidney biopsy detects pathological progression (e.g., increased chronicity) and guides treatment modifications in over 60% of pediatric LN cases. However, pathological class change alone does not dictate short-term outcomes, highlighting initial treatment response as a stronger prognostic indicator. Individualized use of repeat biopsies is recommended for children with proteinuria relapse to optimize management while mitigating procedural invasiveness.