Mesalazine-associated tubulo-interstitial nephritis in inflammatory bowel disease.

The 5-aminosalicylic acid (5-ASA) is currently the treatment of choice for patients with inflammatory bowel disease. It can be administered as sulfasalazine (5-ASA + sulfapyridine), mesalazine (5-ASA + resins or gels) and olsalazine (two molecules of 5-ASA). The recent trend has been to use formulations without sulfapyridine since they produce less side-effects although some cases of nephrotoxicity have been described. We report the case of a young female with Crohn's disease treated with mesalazine (400 mg every 8 hours) over a period of 12 months who developed acute interstitial nephritis. The characteristic features of renal function impairment were an insidious onset with non-specific laboratory data and progression towards a chronic state which partially improved with steroid treatment. In summary, it is important to bear this possibility in mind when confronted by any renal impairment which cannot be related to a relapse of inflammatory bowel disease. Renal function should be monitored routinely in patients receiving mesalazine at least during the first year of treatment and annually thereafter.