Oxalate nephropathy: a three-dimensional view

A 59-year-old woman with chronic renal disease presented in renal failure with a creatinine level of 4.1?mg%. She had undergone a Roux-en-Y gastric bypass performed 10 years earlier. A diagnosis of oxalate nephropathy was made on renal biopsy. Oxalate nephropathy is a known complication of gastric bypass. Calcium and oxalate in the intestine form calcium oxalate complexes that are then excreted. In the setting of fat malabsorption/enteric hyperoxaluria, enteric free fatty acids are elevated and bind calcium within the intestinal lumen, inhibiting the formation of calcium oxalate.