Evaluation of the 13C-triolein breath test for fat malabsorption in adult patients with cystic fibrosis

Background and Aims: A simple non-invasive test not requiring the use of radioactive isotopes is required to assess fat malabsorption in adult cystic fibrosis (CF) patients. Breath tests using substrates labeled with C-13 meet these conditions. The C-14-triolein breath test is sensitive and specific for measuring fat malabsorption, but involves radiation exposure. The aim of this study was to examine the utility of a test using a C-13 label and to determine whether pancreatic replacement therapy would return the test to the values of a normal control group. Methods: (CO2)-C-13 recovery was assessed after an overnight fast in six adult patients with CF, both with and without pancreatic enzyme replacement therapy (PERT) in the usual dose for a light snack, in a randomized order, on different days. Studies were also performed in eight healthy volunteers after oral ingestion. Subjects drank 50 mL of a liquid meal mixed with 200 muL C-13-triolein and breath samples were collected by blowing through a straw into collection tubes every 30 min for 6 h. The effect of gastric emptying was assessed by comparison of oral ingestion with intraduodenal infusion. Intra-individual variability was assessed in nine volunteers by repeating the breath test after drinking the test meal on a separate day. Results: Compared with healthy subjects there was virtually no recovery of (CO2)-C-13 in CF patients without PERT. The median (interquartile range) cumulative percentage dose recovery (cPDR) at 6 h was 3% (0-8) in CF patients compared with 28% (22-41) in healthy controls (P < 0.01). Fat absorption was normalized (37%) (36-43) after ingestion of PERT. Gastric emptying delayed the peak in (CO2)-C-13 recovery, but there was no difference in the cPDR at 6 h. There was no difference in recovery between days 1 and 2. Conclusions: The C-13-triolein breath test is a simple and reproducible method to measure fat malabsorption. The test provides a screening technique for fat malabsorption in adult CF patients and may be useful for monitoring the lowest effective dose of PERT. (C) 2004 Blackwell Publishing Asia Pty Ltd.