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The bile-acid breath test, fecal analysis of labeled bile acids, and Schilling test were used to study bile-acid and vitamin B12 metabolism in 31 patients with ileal Crohn's disease. Results of the bile-acid breath test were positive for 42% of the patients; Schilling test, 42%; fecal analysis of bile-acid labels, 19%. Combination of the tests increased the percentage of positive cases to 65. About 50% of the patients who had positive breath tests had evidence of normal bile-acid absorption, indicating increased bile-acid deconjugation by small-intestinal bacteria. The other 50% had evidence of various degrees of bile-acid malabsorption. Disease activity did not correlate with results of any test. Extent of ileal involvement correlated with results of the bile-acid tests, but not with those of the Schilling test. The study demonstrates that there is a wide spectrum of disturbances of bile-acid and vitamin B12 metabolism in ileitis, and that the tests should be useful in the diagnostic evaluation of patients with proven or questionable Crohn's disease who have diarrhea and malabsorptive abnormalities that could be related to disturbances of bile-acid and vitamin B12 metabolism.

The bile acid breath test was studied to examine its sensitivity for establishing the diagnosis of bacterial overgrowth in comparison to that of the Schilling test and small-intestinal cultures in 12 patients with a stagnant (blind) loop syndrome, as well as in 38 patients who had other conditions with suspected bacterial contamination of the small intestine. The presence of bile acid malabsorption was excluded in all 50 patients by studies of fecal excretion of radioactively labeled bile acids. The bile acid breath test was positive in 100% (12/12) of the patients with a stagnant (blind) loop syndrome, whereas 92% (11/12) had a positive Schilling test and 75% (9/12) a positive small-intestinal culture. The abnormal tests improved only in 2 of 4 patients treated with tetracycline. In the group of 38 patients without demonstrable dilated or blind loops of small bowel who were suspected of having bacterial contamination of small bowel, the bile acid breath test was positive in 53% (20/38), the Schilling test in 39% (15/38), and the small-intestinal culture in 45% (17/38). The difference in the incidence of positive results between the tests in the two patient groups was statistically not significant. The findings of these studies have the following diagnostic implications: (1) Bile acid breath test, Schilling test, and cultures of aspirates from the upper small bowel are of comparable sensitivity in the detection of bacterial overgrowth in the small intestine. (2) A negative bile acid breath test makes the diagnosis of a stagnant (blind) loop syndrome very unlikely.