[Severe tubulo-interstitial nephritis secondary to 5-ASA].

We report a new case of chronic interstitial nephritis in a patient with ulcerative colitis diagnosed in 2002 who was originally treated with 5-ASA. Three years later deterioration of renal function was apparent with an increase in serum creatinine, which was normal before treatment. Withdrawal of 5-ASA led to partial improvement of renal function. In patients with a delayed diagnosis of kidney damage, recovery of renal function is incomplete and, in some cases, the patient even requires some form of renal replacement therapy. We stress the importance of monitoring renal function in patients diagnosed with inflammatory bowel disease treated with this drug.