A Case Study and Review of the Literature on IgA Nephropathy in Crohn's Disease.

IgA nephropathy (IgAN) is the most frequently reported glomerular disease associated with inflammatory bowel disease (IBD), particularly Crohn's disease (CD), although pediatric cases remain rare. We report IgAN in a 16-year-old male with CD following intestinal surgery and during long-term infliximab therapy, with renal impairment occurring independently of bowel disease activity. The patient presented with recurrent macroscopic hematuria, proteinuria, and acute kidney injury despite sustained intestinal remission. Renal biopsy confirmed IgAN (MEST-C: M0, E0, S1, T0, C1). Treatment with renin-angiotensin system (RAS) blockade and corticosteroids resulted in complete renal remission. Infliximab was discontinued, and a subsequent intestinal flare was successfully treated with ustekinumab. This case highlights the importance of vigilant renal monitoring in pediatric CD, particularly in patients with prior intestinal surgery or long-term biologic therapy.