Relapsing tubulointerstitial nephritis in an adolescent with inflammatory bowel disease without aminosalicylate exposure.

A 14-year-old boy presented with ongoing constipation as a manifestation of newly diagnosed Crohn's disease (CD) and a concomitant decline in renal function with biopsy-proven interstitial nephritis. Initiation of steroid therapy and mesalazine was associated with an improvement in symptoms and renal function. We describe a rare case of a 5-aminosalicylic acid (5-ASA)-naïve patient who developed interstitial nephritis in association with CD with no evidence of other primary glomerulopathy. A unique feature of the case being a profound systemic inflammatory response at the time of diagnosis and a relapse in nephritis 2 months after cessation of mesalazine in the absence of any macroscopic colitis.