Determination of protein turnover changes in perioperative patients by the 15N-glycine constant infusion method

The N-glycine constant infusion method was used to study protein turnover in normal adults and perioperative patients. The protein turnover rate (Q), synthetic rate (S) and catabolic rate (C) were derived according to Picou's two-pool system model, and the "end-product averaging technique" showed the 15N-glycine constant infusion method to be reliable, with a reproducibility of +/-5.1%. This measurement can be repeated after a short period, so it should be useful for surgical nutrition study. Our results show the following: Q was significantly increased after operation (3.4 +/- 0.6 to 5.0 +/- 0.5 g protein/kg/d, P less than 0.01), and S (2.6 +/- 0.5 to 3.7 +/- 0.6 g protein/kg/d, P less than 0.05) and C (2.3 +/- 0.5 to 3.9 +/- 0.5 g protein/kg/d, P less than 0.01) were increased as well. This suggests that the protein degradation rate outstripped the synthesis rate on post-operative day three (POD+3) when traditional (glutamine-free) total parenteral nutrition support was used.