Growth Hormone and Bone: Preclinical and Clinical Perspectives.

OBJECTIVE

Growth hormone (GH) is essential for growth and bone metabolism. This article reviews preclinical data that has shaped our understanding of the mechanisms underpinning the effects of GH on bone beyond the downstream activation of insulin-like growth factor-I (IGF-I) generation and summarizes the clinical data of GH deficiency (GHD) and acromegaly on bone health parameters and fracture risk.

METHODS

A literature search was conducted on PubMed using the following key words: GH, IGF-I, bone, GHD, and acromegaly. The discussion of therapy in GHD and patients with acromegaly, and their fracture risk assessment was based on evidence derived from previously published preclinical and clinical studies.

RESULTS

Preclinical and clinical data have demonstrated important pleiotropic effects of GH and IGF-I on bone formation and resorption. GH exerts direct and IGF-dependent and independent effects on bone, while IGF-I acts in an endocrine and autocrine/paracrine manner. In GHD, decreased bone turnover, delayed statural growth, low bone mass, and increased fracture risk are observed, whereas acromegaly is associated with increased bone turnover but decreased lumbar bone mineral density and increased vertebral fracture and osteoarthritis risk. Treatment aimed at normalizing the GH/IGF-I axis decreases the fracture risk in GHD, but not acromegaly.

CONCLUSION

Preclinical and clinical studies have improved our understanding of the role of GH in bone in healthy individuals and in disease states. More research is needed to identify the effects of GH on bone and to determine how best to treat patients with GHD and acromegaly, so that their bone health is optimized.