Interstitial nephritis in patients with inflammatory bowel disease treated with mesalamine

Mesalamines are slow-release formulations of 5-aminosalicylic acid (5-ASA) and are effective as primary treatment and maintenance therapy in inflammatory bowel disease. Interstitial nephritis is a recognized side effect. We report two cases of biopsy-confirmed interstitial nephritis in patients being treated with 5-ASA. Both had a trial of steroid therapy. One patient had partial recovery of renal function but the other patient was in chronic renal failure and likely was approaching the need for dialysis. Interstitial nephritis is an under-recognized complication of 5-ASA therapy. Early identification and withdrawal of this drug can lead to a partial or complete reversal of renal dysfunction.