The Japanese Society of Internal Medicine

A 52-year-old woman was diagnosed with Blau syndrome and rheumatoid arthritis and was treated with prednisolone and methotrexate. Joint pain and skin ulcers were poorly controlled; therefore, mizoribine (MZ; 150 mg/day) was administered once daily from March 2011. In early July 2011, the patient was hospitalized because of acute kidney injury (AKI) and acute pancreatitis. We reasoned that AKI resulted from hyperuricemia during MZ administration because serum concentrations of uric acid (31.6 mg/dL) and MZ (trough level, 5.14 μg/mL) were markedly elevated on admission. MZ should be administered with caution because of the risk of marked hyperuricemia leading to AKI.