Insulin like growth factor 1

Blood samples were drawn from a vein in the antecubital fossa in the morning (10:00–12:00 am). The separated serum samples were stored at −80 °C until they were analyzed. Serum hormone levels were measured using commercially available kits. Ghrelin, insulin and growth hormone were analyzed by enzyme-linked immunosorbent assay: (a) active-ghrelin, (Molecular Devices, Tokyo, Japan; intra-assay coefficient of variation (CV) 2.13% and interassay CV 8.10%); (b) insulin, (TOSHO, Tokyo, Japan; intra-assay CV 2.6% and interassay CV 2.8%); (c) growth hormone, (THOSHO; intra-assay CV 2.6% and interassay CV 2.8%). Serum leptin, insulin-like growth factor-1 and cortisol levels were analyzed by radioimmunoassay: (a) serum leptin, (Hitachi Aloka Medical, Ltd., Tokyo, Japan; intra-assay CV 5.3% and interassay CV 8.1% ); immunoradiometric: (b) insulin-like growth factor-1, (Hitachi Aloka Medical, Ltd; intra-assay CV 1.1% and interassay CV 2.2%) and electrochemiluminescent: (c) cortisol, (Roche Diagnostics, Tokyo, Japan; intra-assay CV 1.68% and interassay CV 2.12%). Insulin resistance was calculated according to the following formula: homeostasis model assessment-insulin resistance=fasting insulin (μU ml⁻¹) × fasting glucose (mg dl⁻¹)/405.