Effect of growth hormone replacement therapy on bone mass, bone metabolism, and body composition in adult patients with growth hormone deficiency

The goal of this study was to assess the effect of recombinant human growth hormone (r-hGH) on bone mass and body composition as well as variables of bone remodeling in adult patients with growth hormone CGH) deficiency. Ten GH-deficient patients (9 men and 1 woman; age range, 20 to 44 years) were randomly separated into 2 groups: group A was given placebo for the first 6 months and r-hGH during the following 6 months; group B was given r-hGH for 12 months. R-hGH was autoinjected subcutaneously every day at the dose of 0.250 IU/kg per week, with a maximal daily dose of 4 IU. Before the study and 6 and 12 months after the start, blood and urine were obtained to measure several variables of bone metabolism; in addition, lumbar bone mineral density (BMD), body composition, and tomographic variables of the femoral quadriceps of the dominant thigh were assessed. BMD was also measured 5 to 17 months after therapy end. Patients treated with r-hGH for 12 months showed a slight but significant increase of BMD at the end of therapy (P < 0.05); nonsignificant changes were found in patients treated for only 6 months. After suspension of therapy, BMD continued to increase slightly in some patients. Body fat decreased significantly (P < 0.05) and lean body mass increased significantly (P < 0.05) during active therapy in both groups. In addition, alkaline phosphatase and osteocalcin increased significantly (P < 0.05) in both groups after 6 months of active therapy. Results of this study suggest that the longer-term use of r-hGH therapy may increase BMD slightly, primarily by stimulating osteoblastic activity; however, a larger, controlled study should be conducted to confirm this.