Effect of postoperative insulin-like growth factor I supplementation on protein metabolism in humans.

Insulin-like growth factor I (IGF-I) has been shown experimentally to exert a nitrogen-sparing effect in both animals and humans. Its effects on protein metabolism during the first 5 days after radical large bowel resection were investigated. Nineteen patients were randomly allocated to receive either human recombinant IGF-I (2 x 80 micrograms/kg body weight subcutaneously, n = 10) or placebo (n = 9) starting on the morning of the first day after operation. All patients received parenteral nutrition (glucose 3 g and nitrogen 0.1 g/kg/day). The mean(s.e.m.) urinary nitrogen:creatinine ratio was significantly reduced in patients who received IGF-I compared with those given placebo (275.0(17.1) compared with 386.3(23.6), P < 0.01). The mean urinary 3-methylhistidine:creatinine ratio and nitrogen balance were lower in the IGF-I group, but not significantly so. Plasma IGF-I concentrations were four times higher in the treated group compared with those in the placebo group. Insulin-like growth factor binding protein 3 (IGFBP-3) increased significantly after the start of IGF-I treatment, compared with mean postoperative levels. The mean blood glucose concentration was significantly lower in the IGF-I group than the placebo group (P < 0.05) but no patient had a hypoglycaemic attack. The authors conclude that IGF-I does not significantly influence the nitrogen balance, but that results indicate a possible nitrogen-sparing effect in patients after major abdominal operations. IGF-I therapy is safe, and may be of value in catabolic patients after serious injury and major operations.