Clinica Chimica Acta 305 (2001) 1–17 www.elsevier.com / locate / clinchim Review Correlations of growth hormone (GH) and insulin-like growth factor I (IGF-I): effects of exercise and abuse by athletes a, b a a c * Elio F. De Palo , Rosalba Gatti , Federica Lancerin , Enrico Cappellin , Paolo Spinella a Clinical Biochemistry Section, Department of Medical Diagnostic Sciences and Special Therapies, University of Padua Medical School, Via Ospedale, 105, 35128 Padua, Italy b Department of Medical and Surgical Sciences, Azienda Ospedaliera di Padova, Padua, Italy c Department of Clinical and Experimental Medicine of the University of Padua, Padua, Italy Received 10 August 2000; received in revised form 12 December 2000; accepted 22 December 2000 Abstract The importance of hormones on body metabolism when physical exercise is carried out has been established for a long time. Growth hormone (GH) is crucial in energy metabolism as well as in body anabolism. Recent studies have increased our knowledge of GH’s mechanisms of action. In particular, insulin-like growth factor I (IGF-I), the main hormone mediating the principal GH effects and other protein structures (i.e. the binding proteins related to these two hormones), has been recognized as playing a crucial role. The biochemical aspects relating to the molecules of the GH / IGF-I axis have been described here. Furthermore, the belief that GH and IGF-I enhance performance has induced an ‘abuse’ of GH (and possibly of IGF-I) by competitive sports athletes and amateurs. The present study outlines the best methods available to uncover abuse, as well as a series of potential research projects to recognize doping. The review also underlines the principal variables measurable in the laboratory and summarizes published reference ranges of these parameters. These biochemical and laboratory profiles describe principal experimental approaches, with the hope that this will stimulate new ideas on the subject of detecting doping practices.  2001 Elsevier Science B.V. All rights reserved. Keywords: Growth hormone; Insulin-like growth factor I (IGF-I); Growth hormone binding protein (GHBP); Insulin-like growth hormone binding proteins (IGFBPs); Doping 1. Introduction Abbreviations: ALS, acid labile sub-unit; GH, growth hormone; Growth hormone (somatotropin) is a polypeptide GHBP, growth hormone binding protein; GHD, growth hormone hormone synthesized and secreted by the somatot- deficiency; GHIH, growth hormone inhibiting hormone; GHR, roph cells of the anterior pituitary (pituitary growth growth hormone receptor; GHRH, growth hormone releasing hormone, pit-GH). Like other protein hormones, it hormone; GLUT, glucose transporter; IGFBP, insulin-like growth factor binding protein; IGF-I, insulin-like growth factor I; IGF-II, originates from a larger precursor moiety (pro-hor- insulin-like growth factor II; pit-GH, pituitary growth hormone; mone of the GH, pro-GH), which, although secreted pro-GH, pro-hormone of the GH; r-GH, recombinant growth by the pituitary, has no physiological significance. hormone Body growth is the generally known role of this *Corresponding author. Tel.: 139-049-827-2485; fax: 139- hormone, but, from the biochemical point of view, it 049-657-391. E-mail address: depalo@ux1.unipd.it (E.F. De Palo). also influences the metabolism of proteins, carbohy- 0009-8981 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0009-8981(01)00378-3