WHOLE-BODY PROTEIN-METABOLISM IN CHILDREN WITH CANCER

Whole body protein synthesis and catabolism were measured using the [r ing-H-2(5)]phenylalanine and [1-C-13]leucine primed constant infusion technique in 32 paediatric patients with cancer at different stages of treatment. Rates of synthesis (S) and catabolism (C) derived from the [ring-H-2(5)]phenylalanine and [1-C-13]leucine models were 4.7 (SD 1. 3) (S) and 6.0 (1.5) (C) g/d/kg, and 5.5 (0.8) (S) and 6.8 (1.2) (C) g /d/kg, respectively. These results show that these two tracer techniqu es give similar results in this study population. Comparison of these values with results previously reported for groups of control children using the [ring-H-2(5)]phenylalanine model (S = 3.69 and 3.93; C = 4. 09 and 4.28 g/d/kg) and the [1-C-13]leucine model (S = 4.32; C = 4.85 g/d/kg) show that rates of synthesis and catabolism were higher in can cer patients than in controls. Thus whole body protein turnover is inc reased in children under treatment for cancer. Other indices of metabo lism such as plasma amino acids and intermediary metabolites were also measured and showed that, although subjects were in isotopic steady s tate, there were significant metabolic changes during the course of th e primed constant infusions used to measure protein turnover.