Growth hormone/insulin-like growth factors axis in children undergoing cardiac surgery

Objectives: To describe the sequential changes in the growth hormone (GH)/insulin-like growth factors axis and their relationship with nitrogen balance in children following cardiac surgery. Design: Prospective, descriptive study. Setting. Pediatric intensive care unit of a university hospital. Patients: Twenty three postoperative cardiac surgical patients after bypass. Interventions: Blood and urine samples were taken on days 1, 2, and 7 of pediatric intensive care unit admission. An intraanes-thesia, presurgery sample was also obtained. Measurements and Main Results: Serum concentrations of insulin, insulin growth factor-I (IGF-I), insulin growth factor binding proteins 1 and 3 (IGFBP-1 and IGFBP-3), growth hormone binding protein (GHBP), and urinary concentrations of GH and free cartisol (UFC) were measured on days 1, 2, and 7 of the study period. G-reactive protein and prealbumin, were also measured in blood samples as conventional markers of inflammatory or nutritional status. Pediatric Risk of Mortality ii score and UFC were used as indicators of acute stress. The nitrogen balance and urinary nitrogen urea excretion were used as markers of catabolic state, Urinary concentrations of GH were high from days 1 to 7, Plasma concentrations of IGF-I and GHBP were low and remained low throughout the study period, IGFBP-3 levels were below normal but without reaching statistical significance. The IGFBP-1 levels were initially high but descended progressively toward normal values. Urinary nitrogen urea production was persistently elevated and was associated with a negative nitrogen balance. No relationship was found between nitrogen balance and IGF-I, prealbumin, or C-reactive protein. Conclusions: A GH-resistant state is observed in postoperative children following cardiac surgery, Stress response is characterized by an elevation of growth hormone secretion that is not followed by the corresponding increment in IGF-l and IGFBP-3 concentrations, These hormonal changes may be permissive for the catabolic state of these patients, IGF-I and IGFBP-1 and -3 are not related to either nitrogen balance or urinary nitrogen urea excretion.