ALTERATIONS IN THE INSULIN-LIKE GROWTH-FACTOR SYSTEM IN TRAUMA PATIENTS

The aim of the present study was to elucidate changes in the growth ho rmone (GH)-insulin-like growth factor (IGF) axis in trauma patients th roughout their stay in the surgical intensive care unit (SICU). The fi rst venous blood sample was obtained within 24 h after admission to th e SICU and before the start of nutritional support; the last sample wa s obtained within 24 h of each patient's discharge from the SICU. All patients were receiving nutritional support at this later time. Contro l subjects were healthy volunteers, matched for age and sex and fasted similar to 18 h before blood sampling. GH in trauma patients was incr eased 25-fold on the first day and was still elevated greater than or equal to 5-fold on the last day. Trauma decreased circulating levels o f both IGF-I (50-60%) and IGF-II (33-45%) throughout the duration of t he patients' stay in the SICU. A sustained reduction in plasma IGF-bin ding protein (BP)-3 (55-75%) was observed in trauma patients throughou t the protocol. In contrast, IGFBP-1 levels increased more than threef old during this same period. Furthermore, IGFBP-1 in these patients ha d undergone posttranslational modification and existed primarily in a highly phosphorylated form. Blood, collected from a cohort (n = 3) of these patients within 24 h of their discharge from the hospital, indic ated that IGF-I and IGF-II were still reduced (30%) and that the decre ase in IGFBP-3 and the elevation in IGFBP-1 were still evident at this time. These results indicate that trauma produces rapid changes in ci rculating IGFs and BPs that largely persist despite adequate nutrition al intake and overall improvement in the patient's condition. Such cha nges in IGFs and their BPs may contribute to the altered muscle protei n balance observed in these patients.