Lactose-[C-13]ureide breath test: A new, noninvasive technique to determine orocecal transit time in children

Background: The lactose-[C-13]ureide breath test (LUBT) is a novel, noninva sive test to determine orocecal transit time. Lactose ureide resists the ac tion of brush border enzymes and is metabolized by colonic bacteria. The pu rpose of the present study was to adapt this breath test for children of va rious age groups and to determine whether it can be applied in infants, new borns, and preterms to study the development of small intestinal motility. Methods: In a group of 20 children (3-17 years) in vitro stool analysis and in vivo LUBT results were compared. From each subject a blank stool sample and a sample produced after induction with unlabeled lactose ureide were i ncubated with 10 mg lactose-[C-13]ureide in small, closed bottles. Ten-mill iliter CO2 samples were aspirated from the bottles using a needle and a syr inge every 30 minutes for 24 hours. All children performed the breath test after induction of 500 mg unlabeled lactose ureide three times the prior da y. A liquid test meal (chocolate milk) with 250 mg lactose-[C-13]ureide was ingested. Breath samples were collected every 15 minutes for 10 hours. In a second group of 32 children (age range, 0-3 years) consisting of 6 childr en between 1 and 3 years of age, 6 infants between 6 and 12 months, 13 infa nts between 0 and 6 months, and 7 preterm infants, only the in vitro stool analysis was performed. Stools were collected for stool incubation, as desc ribed. Results: The mean orocecal transit time in the group of 20 children aged 3 to 17 years was 255 minutes (range, 165-390 minutes). Stool incubations dem onstrated a clear (CO2)-C-13 peak in all infants aged more than 8 months, i ndicating that their colonic bacterial enzymic activity hydrolyses lactose ureide. However, in all infants aged less than 6 months and in preterm infa nts, the (CO2)-C-13 signal was absent, indicating that those subjects were unable to hydrolyze lactose ureide. Conclusion: Infants aged less than 6 months do not host the appropriate bac terial enzymic activity for splitting lactose ureide. The authors conclude that the LUBT can be applied in infants aged more than 8 months, after wean ing to solid foods, to determine orocecal transit time.