ObjectivesTo study the effects of growth hormone administration on insulin-like growth factor I concentration, nitrogen balance, and fuel utilization, and to study its safety in critically ill nonseptic patients.DesignProspective, randomized, placebocontrolled trial.SettingMedical intensive care unit of a university hospital.PatientsEighteen critically ill nonseptic patients were studied for 8 days after admission.InterventionsGrowth hormone (0.1 mg/kg/day) or placebo was administered as a continuous intravenous infusion on the second, third, and fourth days after admission. The study period was 8 days.Measurements and Main ResultsPlasma hormone concentrations were measured every 6 hrs and average daily values were calculated. The 24-hr urinary nitrogen and 3-methylhistidine excretion were measured. Indirect calorimetry was used to calculate fuel utilization. Insulin-like growth factor I concentrations increased in the treatment group from subnormal to normal values and remained increased despite discontinuation of growth hormone treatment (p = .02).Nitrogen balance differed between the groups upon admission:growth hormone group (3.9 +/- 4.1 g/day) vs. controls (13.8 +/- 5.4 g/day), but improved with growth hormone. This finding appeared independent of the imbalance between the groups. The 3-methylhistidine excretion was not different between the groups and did not change during growth hormone administration. Free fatty acids and glycerol concentrations increased during growth hormone treatment, but calculated fuel utilization did not change. During growth hormone treatment, insulin concentrations increased, due to the increased administration of insulin necessary for glycemic control. Side effects other than hyperglycemia were not observed.ConclusionsGrowth hormone administration in a heterogeneous group of critically ill nonseptic patients resulted in normalization of insulin-like growth factor I levels, even after cessation of growth hormone treatment. Nitrogen balance improved, but this change was transient. Hence, growth hormone affects nitrogen balance, probably partly independent of insulin-like growth factor I.(Crit Care Med 1995; 23:665-673)