Tubulointerstitial nephritis as an extraintestinal manifestation of Crohn's disease

Renal manifestations in Crohn's disease—a chronic relapsing inflammatory disease characterized by mucosal ulcerations of the digestive tract—are rare. Tubulointerstitial nephritis has been reported in Crohn's disease, but most cases have occurred in patients treated with 5-aminosalicylic acid derivatives, which are known to be nephrotoxic. In this Case Study, Waters et al. present two cases of tubulointerstitial nephritis occurring in patients with Crohn's disease, and emphasize that physicians should be aware of this serious and under-recognized complication.