Whole-body protein metabolism assessed by leucine and glutamine kinetics in adult patients with active celiac disease

To assess the effect of increased renewal of intestinal epithelial cells on leucine and glutamine (Gln) turnover. 4-hour intravenous infusions of L-[1 -C-13]leucine and L-[2-N-15]Gln were administered to five adult patients wi th active celiac disease in the postabsorptive state. There was a 35% incre ase in leucine flux (micromoles per kilogram per hour) in patients (117 +/- 17) compared with healthy controls (96 +/- 11, P < .03). Gin flux was incr eased by 13% in patients (377 +/- 35) versus controls (335 +/- 16, P < .04) . These results suggest that active celiac disease, characterized by villou s atrophy and crypt cell hyperplasia, is associated with a dramatic increas e in whole-body protein breakdown as assessed by C-13-leucine, which may co ntribute per se to the protein malnutrition status of the patients. The inc rease in Gin utilization as assessed by L-[2-N-15]Gln was moderate. but may have been offset due to the villose atrophy and ensuing reduced intestinal epithelial cell mass. The results are consistent with the concept that inc reased renewal of intestinal epithelial cells represents a sizable fraction of whole-body protein turnover and that Gin is an important fuel for epith elial intestinal cells in vivo. Copyright (C) 1998 by W.B. Saunders Company .