Prevalence of Nephrolithiasis in Malabsorptive Syndromes

Abstract

Patients with inflammatory bowel disease have an increased incidence of nephrolithiasis, especially after resection or bypass of part of the bowel¹. Many of these stones are composed of calcium oxalate though uric acid stones appear to be more common after an ileostomy. Patients with ileal disease have increased absorption of dietary oxalate, with resultant hyperoxaluria, because of increased solubility of oxalate and increased permeability of the colon to oxalate¹. Increased solubility is related to steatorrhea. Unabsorbed fatty acids bind to calcium preventing the formation of insoluble calcium oxalate, thus oxalate remains in solution available for absorption. Fatty acids (and bile acids) also increase the permeability of the colon to oxalate².