Efficacy of growth hormone-replacement therapy: Body composition and bone density

Adults with growth hormone deficiency (GHD), whether of childhood or adult onset, exhibit abnormalities in body composition and bone metabolism. It ha s been suggested that increased body fat may predispose adults with GHD to cardiovascular disease and that reduced bone density increases the risk of fracture. Studies of growth hormone (GH)-replacement therapy in these patie nts have demonstrated consistent effects on body composition with a decreas e in body fat, both subcutaneous and visceral, and an increase in lean mass . Another consistent finding among GH-replacement studies is the significan t effect on markers of bone turnover. Both bone resorption and bone formati on are activated soon after initiation of GH therapy. The effects of GH rep lacement on bone mass are less clear, with variable results among, publishe d studies. The varied duration of GH replacement between studies may explai n the disparate results because bone remodeling is a long-term process. Lon g-term studies (greater than or equal to 18 months) demonstrate that GH rep lacement increases bone density, particularly at the spine and hip. Further studies are needed to address the long-term effect of GH replacement on ca rdiovascular mortality and fracture rates.