End-stage renal disease after bariatric surgery

A 57-year-old woman with morbid obesity (body mass index 41.6), diabetes mellitus, hypertension and obstructive sleep apnea sought bariatric surgery for weight loss. Her pre-operative serum creatinine was 1.0 mg/dL (88.4 μmol/L), and she had no history of renal calculi. She underwent laparoscopic Roux-en-Y gastric bypass surgery with a 75-cm Roux limb. Post-operatively, she was non-adherent with calcium supplementation and had difficulties staying hydrated because of loose bowel movements. She lost 100 lbs (45.5 kg) and her diabetes, hypertension and obstructive sleep apnea resolved. Unfortunately, however, her creatinine gradually rose to 10.8 mg/dL (954.7 μmol/L) 1.5 years after surgery, requiring hemodialysis. The renal biopsy revealed moderate acute tubular injury with extensive calcium oxalate deposition. A diagnosis of oxalate nephropathy was made. The patient remains dialysis dependent despite aggressive calcium supplementation and low oxalate diet. Obesity affects >30% of the US population [1], and bariatric surgery is becoming an increasingly common procedure for its treatment. The Roux-en-Y procedure is considered the bariatric procedure of choice, and 108 000 underwent it in the United States in 2003 [2].