Reproducibility and simplification of 13C-octanoic acid breath test for gastric emptying of solids

Am J Gastroenterol. 1998 Jan;93(1):92-8. doi: 10.1111/j.1572-0241.1998.092_c.x.


Objective: The accuracy of the 13C-octanoic acid breath test is enhanced by breath sampling over 6 h rather than 4 h, but this increases the cost of the test. Our aim was to validate a less costly but accurate sequence of breath sampling for measuring gastric emptying of solids.

Methods: We performed the 13C-octanoic acid breath test and tested its reproducibility relative to simultaneous scintigraphy in 30 healthy volunteers.

Results: There was a significant but weak correlation between t1/2 measured by the two tests (rs = 0.54, p < 0.005), but not between the duration of the lag phase. The differences in the t1/2 measurements between the tests were different between subjects but were highly reproducible within subjects. Within- and between-subject variations of measurements of gastric emptying with the 13C-octanoic acid breath test were not significantly different from the variations observed with scintigraphy. A subset of 11 breath samples collected over 6 h (24 samples) predicted (r2 > 0.95) the variables characterizing the cumulative appearance of 13CO2 in breath; these samples were at 35, 50, 95, 110, 140, 155, 215, 245, 260, 290, and 335 min. The accuracy of this subset of sampling times was confirmed in a separate set of breath test samples over 6 h from the same 30 subjects.

Conclusions: The 13C-octanoic acid breath test for gastric emptying of solids is as reproducible as scintigraphy. A subset of 11 sampling times provides sufficient information to characterize the whole breath-test curve, but the sampling period should be extended to 6 h after dosing.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Breath Tests / methods*
  • Caprylates / analysis*
  • Carbon Isotopes
  • Chromatography, Gas
  • Female
  • Gastric Emptying*
  • Humans
  • Linear Models
  • Male
  • Middle Aged
  • Models, Biological
  • Predictive Value of Tests
  • Radionuclide Imaging
  • Reproducibility of Results
  • Stomach / diagnostic imaging*


  • Caprylates
  • Carbon Isotopes
  • octanoic acid