Growth hormone abuse in athletes: A review

Growth hormone (GH) is being used by elite athletes to enhance performance. The rationale appears to come from studies in adults with GH deficiency, w here GH replacement has been shown to alter body composition so that lean t is sue mass is increased and fat mass is decreased, to enhance aerobic and resistance performance, to increase cardiac output, to enhance thermal adap tation during exertion, to increase collagen syn thesis, and to modify inte rmediary metabolism. Documentation of enhanced performance in athletes, how ever, is currently lacking. Detection of exogenous GH abuse presents a numb er of unique problems, in that endogenous GH is secreted in a pulsatile fas hion and is stimulated by acute exercise. Also, recombinant 22 kDa GH is cu rrently indistinguishable from the endogenous hormone. An international col laborative study group has been established to develop a means of different iating supra-physiological doses of exogenous GH from endogenous GH secreti on in athletes. Current testing strategies center around markers of GH acti on (the insulin-like growth factor system and markers of bone and collagen turnover), and molecular isoforms of GH. Although additional validation wor k is required, a test to detect GH abusers can be implemented in the near f uture.