Plasma insulin-like growth factor-1 (IGF-1) was measured by radioimmunoassay after
acid-ethanol extraction (Nichols Institute of Diagnostics, San-Juan Capistrano, CA). Age-adjusted Z scores of plasma IGF-1 were calculated using values obtained in healthy subjects. Plasma cortisol was measured by radioimmunoassay (Elecsys 2010; Roche diagnostics, Basel, Switzerland). An automatic immunoassay (Perkin Elmer Life Sciences, Groningen, The Netherlands) was used to determine free T4.