Application of a stable isotope (13C) -labeled glycocholate breath test to diagnosis of bacterial overgrowth and ileal dysfunction
Solomons, N.W.; Schoeller, D.A.; Wagonfeld, J.B.; Ott, D.; Rosenberg, I.H.; Klein, P.D.
Journal of Laboratory and Clinical Medicine 90(3): 431-439
1977
ISSN/ISBN: 0022-2143 PMID: 894099 Document Number: 120676
Interval sampling of expired air offers a noninvasive methodology for the study of intestinal physiology. A GC-14C breath test has wide clinical recognition as a test of intestinal bacterial overgrowth or ileal dysfunction. There is need for a nonradioactive, stable isotope analogue of this test, suitable for infants, children and pregnant women, in whom the use of radioisotopes may be inappropriate. Stable isotope labeling and mass spectrometric analysis were applied to development of a GC deconjugation breath test using 13C as the isotopic marker. In 13 adult subjects with a wide range of conditions associated with upper intestinal bacterial overgrowth or ileal dysfunction, the intraluminal deconjugation of standard glycocholate-1-14C-glycine was compared to that of simultaneously administered glycocholate-1-13C-glycine or glycocholate-1,2-13C-glycine. Correlations of net deconjugation as measured by the radioactive isotope and stable isotope labeled bile salt were excellent (correlation coefficient 0.952). Exogenous bile salts did not affect reproducibility of the breath test. There was statistical identity between results of tests using glycocholate-1-13C-glycine or glycocholate-1,2-13C-glycine. The calculated detection limits employing a dose of 7.5 mg/kg body wt of glycocholate-1,2-13C-glycine are 4.7% and 6.2% at the 95% and 99% confidence levels, respectively. This test offers potential advantages of safety and acceptability for infants, children, pregnant women and women at risk of pregnancy.