MEASURING LIQUID GASTRIC EMPTYING TIME USING 13C-GLUTAMINE

Abstract

50 We theorized that glutamine, a preferred fuel of enterocytes, may be ideal substrate to measure liquid gastric emptying time. This method uses non-invasive breath tests and differs from nuclear scanning by being performed in normal posture at bedside. We compared the 13C-glutamine stable isotope determination with the standard nuclear gastric emptying study. Method: Twenty-one consecutive subjects (13 female) aged 9 months to 17 years with scheduled liquid gastric emptying scans were enrolled. The subjects presented with reflux (14/21), feeding disorder (11/21), gastrostomy (8/21), fundoplication (4/21) and pyloroplasty (1 patient). Milk based liquid at 1 ounce per Kg, with a maximum of 8 ounces, after age appropriate fast was administered. In the first ounce of fluid 200 microcuries of technetium - 99m sulfa colloid and 30mg 13C l-glutamine were added. Following the meal, continuous scanning occurred for 60 minutes, followed by intermittent imaging at 90 and 120 minutes. Breath samples were collected in triplicate using a bag and mask and stored in 10-ml vacuutainers in triplicate. Samplings occurred at baseline, every 10 minutes for 60 minutes and at 90 and 120 minutes. Excess 13C in breath samples was measured by isotope ratio mass spectroscopy, and percent of the cumulative total at time intervals derived. Results: The gastric emptying curves were similar, with widest divergence seen in rapid dumping. The 60 minute emptying times correlated at R2 0.735, p<0.0001 ANOVA and the half-emptying time correlated (plot) at R2 0.84, p<0.0001 ANOVA. Conclusion: 13C-glutamine breath test correlates well with radionuclide scanning at wide age ranges and emptying rates. Modifications of the test by additional collection times are likely to improve the test further. (Figure)FIG