WCN26-6768 CLINICAL AND PATHOLOGICAL CHARACTERISTICS OF PATIENTS UNDERGOING REPEAT RENAL BIOPSY IN IGA NEPHROPATHY; A SINGLE CENTER RETROSPECTIVE STUDY

Introduction:IgA nephropathy is one of the most common types of glomerulonephritis and steroid pulse therapy and tonsillectomy is the standard therapy in Japan.In our institution the steroid regimen is determined on pathological findings from the first renal biopsy, patients' comorbidities and individual risks of glucocorticoid toxicity.However some patients experience unfavorable clinical courses such as poor response to treatment or relapse after initial improvement.Therefore we hypothesized that some cases did not received enough immunosuppression partly because we underestimated disease activities.To confirm this hypothesis, we compared the clinical and pathological characteristics of patients with or without repeat renal biopsy.Methods: In our institution, repeat renal biopsies are performed in cases of relapse or no response to the standard treatment.We retrospectively reviewed patients diagnosed with IgA nephropathy by renal biopsy at our institution between January 2001 and September 2025.Exclusion criteria included cases with missing data, initial renal biopsy performed at another institution, or coexistence of other renal diseases.Among these, patients who underwent their first and second biopsy were assigned into the repeat biopsy group.We compared the initial renal biopsy findings between the repeat biopsy group and the nonrepeat biopsy group.Results: In total, 465 patients were included in this study, 442 in the non-repeat biopsy group and 23 in the repeat biopsy group.There was no significant difference in the male-to-female ratio and median ages between two groups (200:242 vs 9:16 and 39.5 vs 39 respectively).There were no significant differences between the groups in terms of BMI, blood pressure, BUN, serum creatinine, creatinine clearance, urinary protein levels, white blood cell count, total cholesterol, IgG, IgA, IgM, or C3 levels.However, serum hemoglobin, total protein, and albumin levels were significantly lower, and hematuria was more severe in the repeat biopsy group.Pathologically, comparison of biopsy findings before treatment revealed that the repeat biopsy group demonstrated a higher proportion of crescentic glomeruli and segmental sclerosis.Immunofluorescence staining revealed significantly higher intensity of fibrinogen deposition in the repeat biopsy group.There were no significant differences in the deposition of IgG, IgA, IgM, C3c or C4c. Conclusion:The repeat biopsy group demonstrated significantly lower hemoglobin, total protein and albumin levels, suggesting a potential association with systemic or nutritional deterioration.The repeat biopsy group had the higher proportion of segmental sclerosis and crescent formation, and higher intensity of fibrinogen deposition in immunofluorescence staining.These findings indicate higher disease activity at the initial biopsy.Since the optimal treatment for IgA nephropathy remains undefined and the treatment strategy varies widely among institutions, identifying the characteristics of patients requiring repeat biopsy may provide valuable insights into appropriate treatment strategies in clinical practice.More aggressive immunosuppressant regimen might be appropriate for clinically and pathologically active IgA nephropathy.I have no potential conflict of interest to disclose.I did not use generative AI and AI-assisted technologies in the writing process.