Detection of deconjugation of bile salts with a 14CO 2 breath test

Abstract

LTERED metabolism of bile acids, since it is often readily treatable, is recognized as an important cause of diarrhea and steatorrhea. The diagnosis can be confirmed by thin-layer chromatography of bile acids obtained from jejeunal aspirations. However, this technique is available in only a few centers and entails some risk and discomfort for the patient. This risk can now be avoided and the diagnosis made with a 14C02 breath test. The following case illustrates the use of this technique. This patient was a 48-yr-old woman who had a Billroth II gastrectomy several years ago for a duodenal ulcer. Her major complaint over the past 2 yr was frequent incapacitating diarrhea that was typical of that found in patients with fat malabsorbtion. The differential diagnosis included a disturbance of the entereohepatic circulation of bile caused by an overgrowth of bacteria in the blind loop of duodenum. Bacteria deconjugate bile salts to the conjugating amino acid, glycine or taurine, and the bile acid. The amino acid is absorbed, the bile acid is absorbed or precipitated, and the subsequent reduction in the concentration of bile salts in the proximal small intestine results in fat malabsorbtion.