[Case of suspicious lansoprazole-associated collagenous colitis in ANCA-associated nephritis]

In January 2003, a 70-year-old female consulted a doctor for a fever of unknown origin. She had microscopic hematuria, proteinuria, BUN 41 mg/dL, Cr 2.1 mg/dL and MPO-ANCA 44 U/mL, and was suspected of having ANCA-associated nephritis. A renal biopsy was not conducted because the patient had just one kidney. She was treated with prednisolone (PSL ; 40 mg/day). Subsequently, because of Cr level improvement, the amount of PSL was decreased. In October 2006, the patient again had microscopic hematuria, proteinuria and a slightly elevated Cr level. Lowering of BP and dehydration caused by a common cold were considered to be the cause of her renal dysfunction. She was admitted to Fukuoka University Hospital for 2 weeks, where she received diet therapy and a changed medication schedule in which furosemide was stopped and the dose of enalapril was decreased from 5 mg/day to 2.5 mg/day. Because the MPO-ANCA level was < 10 EU, the amount of PSL was not changed. After 11 months, treatment with lansoprazole at 30 mg/day was started. At the end of the same month, however, she exhibited gait disturbance due to swelling, redness and tenderness in the bilateral pedal joints. After one month of receiving lansoprazole, she experienced a high fever and an elevated Cr level. Accordingly she was again admitted to the hospital, where she was diagnosed with venous thrombosis in the lower limbs, and warfarization was begun. Her condition improved, gradually, and she was discharged from the hospital. After the discharge, she began to exhibit watery diarrhea three to four times per day. Therefore, treatment with warfarin potassium was stopped 50 days after it was begun. In spite of the cessation of warfarization, the diarrhea continued. She underwent bacterial culturing and lower endoscopic examinations (no biopsy was done), which showed erosion of the colon, but the cause of the diarrhea was not found. After 181 days of treatment with lansoprazole, administration of this drug was stopped. The symptoms disappeared within 5 days. There have been few reports of collagenous colitis with chronic diarrhea, but a good prognosis has been described in these cases. Clinicians should consider drug treatment as a possible cause of collagenous colitis in the case of patients with chronic diarrhea of unknown origin during the administration of medication.