Hyperoxaluria and calcium oxalate nephrolithiasis after jejunoileal bypass.

Patients with ileal disease, ileal resection, and jejunoileal bypass are at increased risk of forming calcium oxalate renal calculi because of enhanced absorption of dietary oxalate. Intraluminal solubility of oxalate is an important determinant for hyperabsorption and may be regulated by intraluminal concentration of calcium and fatty acids. Malabsorbed bile salts and fatty acids may alter intestinal permeability, leading to increased passive diffusion of oxalate. Management includes a diet low in oxalate and fat content, dietary calcium of 750 mg/day, and cholestyramine.