A Case of Chronic Calcium Oxalate Nephropathy due to Short Bowel Syndrome and Cholecystectomy

Background: Oxalate nephropathy is a rare disease. Especially chronic oxalate nephropathy still has many unknown aspects as compared to acute oxalate nephropathy with relatively well-known causality. Case Presentation: The patient was a 70-year-old woman who had a history of small bowel resection 25 years before, cholecystectomy 10 years before, and renal stones (calcium oxalate stones) 7 years before. She had been suffering from chronic diarrhea and had been treated by a local physician. The patient was found to have renal dysfunction (creatinine 3.09 mg/dL, eGFR 12.3 mL/min/1.73 m2, hemoglobin 7.8 g/dL) and was referred to our department. The patient was admitted to our hospital for further investigation. Renal ultrasound showed hepatorenal echo contrast in an opposite manner and clear contrast between the renal cortex and medullary pyramid. Renal biopsy was performed, and histological examination showed tubulointerstitial disorder due to deposition of calcium oxalate. Daily urinary excretion of calcium oxalate was significantly increased. The patient was encouraged to drink water and administered vitamin B6, citric acid, K and Na hydrate. Thereafter, her symptoms improved. Conclusion: Case reports of chronic oxalate neuropathy are rare in the literature, and its underlying mechanism has not been understood. Our patient had a history of small bowel resection and cholecystectomy. We considered that her short bowel syndrome had influenced the development of calcium oxalate nephropathy.