Validation in an animal model of the carbon 13-labeled mixed triglyceride breath test for the detection of intestinal fat malabsorption.
OBJECTIVE
To determine, in a rat model of fat malabsorption, the potency of the carbon 13-labeled mixed triglyceride ((13)C-MTG) breath test as a noninvasive, patient-friendly replacement for classic fat balance studies.


METHODS
Comparison of the percentage of fat absorption, detected by fat balance, with the (13)CO(2) recovery of the (13)C-MTG breath test in rats fed high-fat chow and varying amounts of the lipase inhibitor, orlistat (0, 50, 200, and 800 mg per kilogram of chow), for 5 days.


RESULTS
On orlistat administration, total fat absorption decreased from 80.2% +/- 2.2% to 32.8% +/- 3.7% (mean +/- SEM, 0 mg and 800 mg of orlistat per kilogram of chow, respectively; P <.001). Correspondingly, breath (13)CO(2) recovery from (13)C-MTG at 6 hours decreased from 84.5% +/- 7.8% to 42.0% +/- 1.5% of the dose (0 mg and 800 mg of orlistat per kilogram of chow, respectively; P <.001). The 6-hour recovery of breath (13)CO(2) appeared to be highly correlated with the percentage of fat absorption (r = 0.88, P <.001). In rats with fat absorption higher than 70%, however, the coefficient of variation of the (13)C-MTG breath test was 3-fold larger than that of the fat balance.


CONCLUSIONS
The (13)C-MTG breath test could potentially replace the fat balance method for comparing fat absorption efficacy between groups. Yet, a considerable interindividual variation of the (13)C-MTG breath test under conditions of relatively mild fat malabsorption does not support its application for diagnostic purposes in individuals.
Kalivianakis
M
M
Groningen University Institute for Drug Exploration, Center for Liver, Digestive and Metabolic Diseases, Department of Pediatrics, University Hospital Groningen, The Netherlands.
Elstrodt
J
J
Havinga
R
R
Kuipers
F
F
Stellaard
F
F
Sauer
P J
PJ
Vonk
R J
RJ
Verkade
H J
HJ
D000818:Animals; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis; D002247:Carbon Isotopes; D002849:Chromatography, Gas; D004041:Dietary Fats / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005223:Fats / Q000032:analysis; D005243:Feces / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D007408:Intestinal Absorption; D007783:Lactones / Q000494:pharmacology; D008049:Lipase / Q000037:antagonists & inhibitors; D008055:Lipids / Q000097:blood; D008286:Malabsorption Syndromes / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D000077403:Orlistat; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides
D002247:Carbon Isotopes; D004041:Dietary Fats; D004791:Enzyme Inhibitors; D005223:Fats; D007783:Lactones; D008055:Lipids; D014280:Triglycerides; D002245:Carbon Dioxide; D000077403:Orlistat; D008049:Lipase