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

The aim of the present study was to elucidate changes in the growth hormone (GH)-insulin-like growth factor (IGF) axis in trauma patients throughout their stay in the surgical intensive care unit (SICU). The first venous blood sample was obtained within 24 h after admission to the SICU and before the start of nutritional support; the last sample was obtained within 24 h of each patient's discharge from the SICU. All patients were receiving nutritional support at this later time. Control subjects were healthy volunteers, matched for age and sex and fasted similar to 18 h before blood sampling. GH in trauma patients was increased 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 of both IGF-I (50-60%) and IGF-II (33-45%) throughout the duration of the patients' stay in the SICU. A sustained reduction in plasma IGF-binding protein (BP)-3 (55-75%) was observed in trauma patients throughout the protocol. In contrast, IGFBP-1 levels increased more than threefold during this same period. Furthermore, IGFBP-1 in these patients had 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, indicated that IGF-I and IGF-II were still reduced (30%) and that the decrease in IGFBP-3 and the elevation in IGFBP-1 were still evident at this time. These results indicate that trauma produces rapid changes in circulating IGFs and BPs that largely persist despite adequate nutritional intake and overall improvement in the patient's condition. Such changes in IGFs and their BPs may contribute to the altered muscle protein balance observed in these patients.