Growth Hormone Therapy in Adults

Growth hormone (GH) is classically linked with linear growth in childhood but continues to have important metabolic actions throughout life. GH deficiency in adulthood causes a distinct syndrome with significant morbidities. These include increased total and visceral fat, decreased muscle mass and aerobic capacity, affective disturbances, abnormal lipids, and increased vascular mortality, all of which are ameliorated with GH replacement. The possibility of adult GH deficiency (AGHD) should always be considered in individuals with a history of childhood GH deficiency or significant hypothalamic-pituitary damage, and the diagnosis should then be confirmed by biochemical testing. Adult GH dosing is much lower than that in pediatric practice, as appropriate for physiologic reconstitution. Hormonal side effects are minimized by stepwise dose titration. Lingering concerns remain regarding the possibility of increased cancer risk with long-term treatment, but this hazard has not been unequivocally demonstrated. Compared with AGHD, there is much less information about GH replacement in other diseases or in normal aging, or about the use of supraphysiologic GH doses to treat catabolic states. In critical illness, high-dose GH therapy has proven clearly harmful, and the balance of risks and benefits of GH administration in most adult contexts other than AGHD has not been defined.