HUMAN GROWTH-HORMONE KINETICS IN CRITICALLY ILL PATIENTS

Several studies have shown that exogenous human growth hormone (HGH) e xerts an anabolic effect on protein metabolism in surgical patients wi th mild or moderate catabolism. However, contradictory results have be en demonstrated in polytrauma patients where HGH did not improve prote in metabolism. Aim of this study was to evaluate whether the pharmakok inetics of recombinant biosynthetic human GH (r-HGH) are altered in cr itically ill patients. After an overnight fast, r-HGH was infused at a rate of 460 mu g/h/kg/bw during 120 min to five intensive care unit ( ICU) patients. The patients were catabolic (nitrogen balance -11 +/- 0 .5), showed normal liver function, and only one patient had a slightly impaired kidney function (creatinine > 1.5 mg/dI). Endogenous GH secr etion was suppressed by continuous infusion of 50 mu g/m(2)/h somatost atin. From plasma GH curves. elimination half life (t1/2kle), whole bo dy clearance (Cltot) and steady state distribution space (DS) were cal culated in an open two compartment model. Additionally, the effects of r-HGH infusion on plasma insulin, glucagon and amino acid concentrati ons were evaluated. T1/2kle was 19.6 +/- 2.3 min, Cltot 2.9 +/- 0.4 ml /kg/bw/min and DS 76.4 +/- 3.8 ml/kg/bw for 90 min. The plasma levels of total amino acids including the branched chain amino acids valine, leucine and isoleucine and of glutamine were significantly higher duri ng r-HGH infusion than during the basal and somatostatin periods. In c onclusion, the elimination of r-HGH in catabolic ICU patients is not d ifferent from that of healthy volunteers.