Growth hormone (hGH) presents pleiotropic effects in many tissues encompassing a diverse range of physiological actions. Its complexity as a family of hormones with different isoforms and different somatotroph molecular functions continues to challenge the status quo of our understanding of its release, function, and signaling. Owing to the fact that the majority of the literature has viewed hGH from the perspective of the primary 22 kD monomer, further investigation is needed as to the influence and biological activity of other aggregate and splice variant isoforms that are released into circulation. Its role over the life span and with supplementation yields equivocal results with more study needed. Testing for the use of hGH has progressed, and the first positive test was recently documented. Understanding of pituitary function and physiology will remain complex until the use of a broader range of analytical techniques, including assays, becomes mainstream.
1Human Performance Laboratory, Department of Kinesiology, 2Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT; 3Military Performance Division, The U.S. Army Research Institute of Environmental Medicine, Natick, MA
Address for correspondence: William J. Kraemer, Ph.D., FACSM, Professor, Human Performance Laboratory, Department of Kinesiology Unit 1110, 2095 Hillside Road, University of Connecticut, Storrs, CT 06269 (E-mail: William.Kraemer@uconn.edu).