Glutamine metabolism in Crohn's disease: A stable isotope study

Abstract

Aims: To determine whether chronic intestinal inflammation alters glutamine utilization, six 317 6 yr-old patients with Crohn’s disease and an agematched group of 6 healthy subjects received 7-h intravenous infusions of L[5,5,5-H3]leucine, along with an infusion of L-[1C]glutamine delivered intravenously for the first 3.5 h, and via a nasogastric tube for the subsequent 3.5 hrs. None of the patients was receiving any nutritional supplement or antiinflammatory drug. All were in remission (Crohn’s disease activity index o 150) and in a near-normal nutritional status. Methods: We used plasma H3-a-ketoisocaproate to determine leucine appearance rate (Ra), and plasma C-glutamine and breath CO2 to determine glutamine Ra and oxidation, respectively. The fraction of enteral glutamine undergoing uptake in the splanchnic bed was determined from the difference in plasma C-glutamine enrichments between the intravenous and nasogastric C-glutamine infusion periods. Results: Neither leucine Ra, nor plasma glutamine concentration (526740 vs. 530750 mmol/l), glutamine Ra (364719 vs. 355724 mmol kg 1 h ), or splanchnic glutamine uptake (6175 vs. 6572%) differed between groups. In both groups, glutamine oxidation rose when the glutamine tracer was supplied enterally, compared with the intravenous route (7076 vs. 3972% in patients; 6972 vs. 3871% in controls), but did not differ between groups. Conclusion: When in remission, patients with Crohn’s disease have normal rates of proteolysis, and glutamine production, utilization, oxidation, and splanchnic uptake. The data suggest there is no obvious requirement for glutamine in patients with quiescent Crohn’s disease. & 2004 Elsevier Ltd. All rights reserved.