Evaluation of fat utilization in paediatric Crohn's disease using 13C-labelled fat

Carbon-13 breath tests provide a safe and noninvasive way of assessing nutrient absorption and utilization. Disordered protein and carbohydrate metabolism have been reported in children with Crohn's disease, but little is known about their fat utilization. To assess fat oxidation, 13C-Hiolein was administered to 11 children with active Crohn's disease (age range, 10.5-16.9 years; mean, 12.6) before and after treatment with steroids. Expired breath samples were collected at hourly intervals for 12 h, and 13CO2 excretion was measured by mass spectrometry. The mean 95% confidence interval (CI) time to peak 13CO2 excretion was 9 h (range, 7.73-9.97) before treatment and 6.95 h (range, 5.75-8.15) after treatment (p < 0.02). Mean 95% CI cumulative 13CO2 excretion up to peak time (7 h) was 47.53% (range, 24-69%) before treatment and 68.7% (range, 35-80.5%) after treatment with steroids (p < 0.02). Our results demonstrated impaired lipid utilization during active disease and improvement following steroid treatment. The oral 13C-Hiolein test is simple and noninvasive, and its results are reproducible. It provides a new method for estimating fat utilization in paediatric patients, along with the possibility of discriminating between patients with and without impaired utilization during the acute phase of the disease.