PULSATILE NATURE OF GROWTH-HORMONE LEVELS IN CRITICALLY ILL TRAUMA VICTIMS

Background. circulating growth hormone (GH) levels in normal persons f luctuate widely because of pulsatile GH secretion. It is not known whe ther this pulsatile nature and rhythmicity exist in severe injury. The se data become necessary to decide the timing of supplementary GH admi nistration for its optimal utilization. The purpose of this study was to investigate the GH circadian variation with respect to that of insu lin-like growth factor-1 (IGF-1), insulin, C-peptide, and cortisol in the early flow phase of injury. Methods. Plasma GH, IGF-1, insulin, C- peptide, and cortisol levels were measured at 1-hour intervals during 24 hours (8 AM to 8 AM) in 10 severely injured adults with multiple tr auma during the early catabolic flow phase 24 to 48 hours after injury , when patients received maintenance fluids without calories or nitrog en. Results. The 24-hour integrated GH concentration is not different from either 12-hour mean diurnal or 12-hour mean nocturnal or mean 8 A M GH concentration. Pulsatile GH bursts persist in injured patients du ring both day and night. Pulsatile bursts do not exist for IGF-1, insu lin, and C-peptide. The plasma levels of cortisol show time-dependent daily maximum and minimum levels. Conclusions. Pulsatile GH bursts per sist in injured patients but less frequently than seen in normal perso ns. The time of bolus administration of GH to augment the anabolic GH action in patients with trauma does not matter; however, for convenien ce morning administration may be preferable for patients in the intens ive care unit.