Growth hormone therapy in health and disease: could GH and IGF-I combination therapy combat the somatopause?

Recombinant human growth hormone (rhGH) has allowed investigations of the role of GH and identified the effects of rhGH replacement in GH-deficiency (GHD). Both obese and elderly subjects with low insulin like-growth factor-I (IGF-I) levels have functional GHD. Administration of rhGH to elderly subjects with low IGF-I levels results in reversal of changes associated with GHD. These changes are similar to those shown in adults with GHD with rhGH replacement. RhGH replacement in the elderly and obese has been compromised by side effects, due to hypersensitivity. Doses are required to be titrated to individual needs. Insulin like growth factor-I (IGF-I) mediates some of the metabolic actions of GH and has both GH-like and insulin-like actions. Both GH and IGF-I have a net anabolic effect enhancing whole body protein synthesis improving anthropometry in GHD. Both hormones have been used in catabolism and have been effective in counteracting the protein wasting effects of medicines such as glucocorticoids. IGF-I may be an appropriate combination agent to use in conditions where carbohydrate metabolism is impaired. The pendulum of research has progressed towards IGF-I and it may be possible that the two can be used together to treat the sarcopenic effects of the somatopause, with an application for use in obesity?