Bile composition in patients with ileal resection due to Crohn's disease.

Patients with Crohn's disease (CD) have an increased risk of developing gallstones, but the mechanisms are unknown. In a previous study, we found a subnormal cholesterol saturation in the bile of patients with short ileal resections due to CD. The aim of this study was to test the hypothesis that (a) CD patients with a long ileal resection have an altered biliary composition and (b) that CD patients with short or long ileal resection have an increased content of bilirubin in their bile. Biliary lipid composition, cholesterol saturation, bile acid pattern, and bilirubin concentration were determined in fasting duodenal bile of 10 CD patients with long ileal resections and in 4 patients with short resections. Ten healthy subjects served as controls. Cholesterol saturation was significantly lower in those CD patients who had a long or short resection compared with the healthy subjects. Bile acid composition in the CD patients was characterized by a significant decrease in the deoxycholic acid fraction and a prominent increase in the ursodeoxycholic acid fraction. The bilirubin concentrations, expressed as micromoles of bilirubin per millimole bile acid, were 45-50% higher in patients who had a long or a short ileal resection compared with healthy controls. Based on these results, CD patients who had had an ileal resection seem not to be at an increased risk of cholesterol gallstone formation but rather at risk of developing pigment stones.