GASTROINTESTINAL HANDLING OF [1-C-13]PALMITIC ACID IN HEALTHY CONTROLS AND PATIENTS WITH CYSTIC-FIBROSIS

Aim-To examine the gastrointestinal handling of [1-C-13]palmitic acid given as the free acid by measuring the excretion of C-13 label in sto ol in 16 healthy children and 11 patients with cystic fibrosis on thei r habitual enzyme replacement treatment. Methods-After an overnight fa st, each child ingested 10 mg/kg body weight [1-C-13]palmitic acid wit h a standardised test meal of low natural C-13 abundance. A stool samp le was collected before the test and all stools were collected thereaf ter for a period of up to five days. The total enrichment of C-13 in s tool and the species bearing the C-13 label was measured using isotope ratio mass spectrometry. Results-The proportion of administered C-13 label excreted in stool was 24.0% (range 10.7-64.9%) in healthy childr en and only 4.4% (range 1.2-11.6%) in cystic fibrosis patients. The en richment of C-13 in stool was primarily restricted to the species cons umed by the subjects (that is as palmitic acid). Conclusion-There does not appear to be a specific defect in the absorption of [1-C-13]palmi tic acid in patients with cystic fibrosis. The reasons why cystic fibr osis patients appear to absorb more of this saturated fatty acid than healthy children is not clear and requires further investigation.