The effect of the site of lesion and extent of resection on duodenal bile acid concentration and vitamin B12 absorption in Crohn's disease.

Duodenal bile acid concentration following a standard meal, glycine/taurine (G/T) ratio, vitamin B12 absorption, and faecal fat were determined in 79 patients with Crohn's disease. Intestinal resection had been made in 50 patients before the study, and no evidence of recurrence was present at the time of the study. Among 46 patients subjected to ileal resection of 10-180 cm, a reduced duodenal bile acid concentration and vitamin B12 malabsorption was almost invariably present when 50 cm or more of ileum had been removed. Patients with smaller resections and unoperated patients did not show a consistent pattern. Vitamin B12 absorption and duodenal bile acids were of equal value as indicators of ileal dysfunction with the exception that, in 10 ileostomy patients, duodenal bile acids were decreased in every case, but vitamin B12 absorption only when 80 cm of ileum or more had been resected. G/T-ratio was related to the extent of ileal resection-being elevated after large resections (80 cm or more)-but not to the presence of an abnormal flora. Faecal fat was much more elevated in ileostomy patients with large ileal resection (80 cm or more) than in unoperated patients and patients without an ileostomy.