Infliximab is a chimeric anti-
tumor necrosis factor-alpha monoclonal antibody. Infusion related reactions and
infection are well known side effects of
infliximab; however, renal complications have not been well recognized. We report on a patient with late onset-
acute tubulointerstitial nephritis (ATIN)
after treatment with
infliximab and
mesalazine for
Crohn's disease. A 25-year-old woman was admitted with a purpuric
rash on both lower extremities and
arthralgia. She had been diagnosed with
Crohn's disease 5.6 years previously and had been treated with
mesalazine and
infliximab. Serum
creatinine level, last measured one year ago, was elevated from 0.6 mg/dL to 1.9 mg/dL. Results of urinalysis, ultrasound, and serologic examinations were normal. With a tentative diagnosis of
Henoch-Schonlein purpura, oral
prednisolone was given, and serum
creatinine decreased to 1.46 mg/dL, but was elevated to 2.6 mg/dL again at two months after discontinuation of
prednisolone. Renal biopsy indicated that ATIN was probably induced by
drug, considering significant infiltration of eosinophils. Concomitant use of
infliximab with
mesalazine was supposed to trigger ATIN. Oral
prednisolone was administered, and serum
creatinine level showed partial recovery. Thus, ATIN should be suspected as a cause of renal impairment in
Crohn's disease even after a long period of maintenance treatment with
infliximab and
mesalazine.