13C-trioctanoin: a nonradioactive breath test to detect fat malabsorption
Watkins, J.B.; Schoeller, D.A.; Klein, P.D.; Ott, D.G.; Newcomer, A.D.; Hofmann, A.F.
Journal of Laboratory and Clinical Medicine 90(3): 422-430
1977
ISSN/ISBN: 0022-2143 PMID: 894098 Document Number: 121931
Fat malabsorption may be accurately detected in adults by measuring the excretion of 14CO2 in breath following oral administration of a tracer dose of 14C-labeled triglyceride. To detect fat malabsorption in children and in women of child-bearing age without radiation hazard, the use of trioctanoin labeled with the stable, nonradioactive isotope 13C has been inaugurated and validated for use in this breath test. Children (9) aged 3 mo-5 yr were evaluated for fat malabsorption. Results with the 13C-trioctanoin breath test were compared to those obtained by a quantitative 72 h fat balance study. The cumulative excretion of 13CO2 by 2 h was 25 .+-. 2.5% (ave. .+-. SD) of the dose in patients with normal fat absorption and provided a clear differentiation (P < 0.001) from the 3.5 .+-. 2.5% of the dose excreted by those with steatorrhea due to untreated pancreatic insufficiency resulting from cystic fibrosis. Addition of exogenous pancreatic enzymes improved fat absorption and increased 13CO2 excretion 4-fold. The correlation between the percent of fat intake excreted and the cumulative 13CO2/mmol CO2 excreted by 3 h was very good (r = -0.88) in all patients. The 13C-trioctanoin breath test provides accurate detection of fat malabsorption in children with pancreatic insufficiency. This noninvasive technique is more convenient than 72 h stool collection and permits safe and sensitive metabolic studies in children without exposure to radiation.