Faecal bile acid analysis and intestinal absorption in Crohn's disease before and after ileal resection

Faecal bile acids were analysed by gas chromatography in 104 patients. Total bile acids exceeded 1.5 mmol/24 h in 33% of forty‐five unoperated patients and in 90% of those having undergone an ileal resection. Lithocholic and deoxycholic fractions were lower in the unoperated patients than in the control group ( P < 0.05 and P < 0.005) and much lower after ileal resection than in unoperated patients ( P < 0.001). A significant correlation ( r = 0.58; P < 0.001) was found between total bile acids and relative proportions of primary bile acids in operated patients, untreated by antibiotics or sulfasalazine. Dihydroxy bile acids (predominantly chenodeoxycholic acid) correlated with faecal weight in unoperated patients ( r = 0.47, P < 0.01) and in 0–50 cm ( r = 0.69, P < 0.001) and 50–100 cm ( r = 0–63, P < 0.01) ileal resection groups. Our results suggest that the frequently altered bile acid composition is related to a shortening of colonic transit time which reduces the exposure of primary bile acids to bacterial 7α‐dehydroxylase.