The importance of growth hormone replacement therapy for bone mass in young adults with growth hormone deficiency.

Growth hormone (GH) plays an important role in longitudinal bone growth in childhood, accrual of peak bone mass, and bone preservation in adults. GH deficiency (GHD) is associated with reduced bone turnover and decreased bone mineral density (BMD), especially in patients with childhood-onset GHD. GH replacement therapy stimulates bone remodeling and causes an initial decrease in BMD due to bone resorption and expansion of the remodeling space. This is followed by increased bone formation and a significant increase in BMD that continues with prolonged GH therapy. The effect appears to be dose-dependent. GH dose should be individualized based on factors such as age, oral estrogen therapy, and IGF-I levels. Young GH-deficient adults with low BMD measurements by dual-energy X-ray (DEXA) scan should be considered for GH replacement therapy to reduce future fracture risk.