[13C]octanoic acid breath test for gastric emptying of solids: accuracy, reproducibility, and comparison with scintigraphy

Gastroenterology. 1997 Apr;112(4):1155-62. doi: 10.1016/s0016-5085(97)70126-4.


Background & aims: Previous work suggested that a breath test using 13C accurately measures gastric emptying of solids. Thus, breath test half emptying time (t1/2) minus 66 minutes was claimed to estimate accurately t1/2 by scintigraphy. The aim of this study was to evaluate the accuracy and reproducibility of this breath test in healthy subjects.

Methods: Fifteen volunteers (8 men and 7 women; mean age, 41 +/- 13 years) underwent simultaneous scintigraphy and [13C]octanoic acid breath test. Scans and breath samples were obtained every 15 minutes for 4 and 6 hours, respectively. The breath test was repeated three times within a 3-week period.

Results: Parameters from scintigraphy and breath test were not correlated significantly. Differences of lag phase and t1/2 between the two tests were highly variable (range for t1/2, -33.1 to 169.6; mean, 48.0 minutes). Increasing breath test "duration" (samples over 4, 5, or 6 hours) yielded decreasing estimates of the lag phase and t1/2. Although widely different values were observed in some subjects, repeated breath tests showed a high degree of reproducibility within individuals (mean coefficient of variation, 12%).

Conclusions: [13C]Octanoic acid breath test for gastric emptying of solids requires further validation before it can substitute for scintigraphy as a diagnostic test, but it seems useful for intraindividual comparisons.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Breath Tests*
  • Caprylates*
  • Carbon Isotopes
  • Evaluation Studies as Topic
  • Female
  • Gastric Emptying*
  • Humans
  • Male
  • Middle Aged
  • Radionuclide Imaging
  • Reproducibility of Results
  • Stomach / diagnostic imaging*


  • Caprylates
  • Carbon Isotopes
  • octanoic acid