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

Objectives: To describe the sequential changes in the growth hormone (GH)/i nsulin-like growth factors axis and their relationship with nitrogen balanc e 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 pe diatric intensive care unit admission. An intraanes-thesia, presurgery samp le was also obtained. Measurements and Main Results: Serum concentrations of insulin, insulin gro wth factor-I (IGF-I), insulin growth factor binding proteins 1 and 3 (IGFBP -1 and IGFBP-3), growth hormone binding protein (GHBP), and urinary concent rations 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 a cute 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 rema ined low throughout the study period, IGFBP-3 levels were below normal but without reaching statistical significance. The IGFBP-1 levels were initiall y high but descended progressively toward normal values. Urinary nitrogen u rea production was persistently elevated and was associated with a negative nitrogen balance. No relationship was found between nitrogen balance and I GF-I, prealbumin, or C-reactive protein. Conclusions: A GH-resistant state is observed in postoperative children fol lowing cardiac surgery, Stress response is characterized by an elevation of growth hormone secretion that is not followed by the corresponding increme nt in IGF-l and IGFBP-3 concentrations, These hormonal changes may be permi ssive for the catabolic state of these patients, IGF-I and IGFBP-1 and -3 a re not related to either nitrogen balance or urinary nitrogen urea excretio n.