title: Reproducibility and simplification of 13C-octanoic acid breath test for gastric emptying of solids.
abstract: 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.
authors.affiliation: Mass Spectrometry Core Laboratory, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Choi
authors.forename: M
authors.initials: M
authors.lastname: Camilleri
authors.forename: D D
authors.initials: DD
authors.lastname: Burton
authors.forename: A R
authors.initials: AR
authors.lastname: Zinsmeister
authors.forename: L A
authors.initials: LA
authors.lastname: Forstrom
authors.forename: K S
authors.initials: KS
authors.lastname: Nair
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods*; D002210:Caprylates / Q000032:analysis*; D002247:Carbon Isotopes; D002849:Chromatography, Gas; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D013270:Stomach / Q000000981:diagnostic imaging*
chemical_list: D002210:Caprylates; D002247:Carbon Isotopes; C031492:octanoic acid