Growth hormone, insulin-like growth hormone-i axis, and bone fragility

Abstract

Growth hormone (GH) and insulin-like growth factor-I regulate skeletal physiology, and both excessive and deficient levels affect bone remodeling and alter bone microstructure. Bone quality is affected more than bone quantity, and vertebral fractures (VFs) are an early phenomenon of impaired bone health. Since fractures cannot be accurately predicted by areal bone mineral density, emerging data demonstrate that a morphometric approach is essential for evaluating bone health given their predictive role in both clinical settings. Several novel tools assessing bone quality and bone remodeling have been proposed as alternative or additional methods for the prediction of fractures. Prompt disease control of acromegaly and GH replacement therapy for GH deficiency (GHD) are fundamental for the restoration and maintenance of skeletal health. Replacement of other pituitary deficiencies, especially sex hormones, should be provided for advanced bone outcomes in patients with GHD with cautious replacement of glucocorticoids and levothyroxine to avoid overtreatment. Vitamin D has proved to be very effective in the prevention of VFs in the case of acromegaly and in improvement of bone microarchitecture when combined with GH replacement therapy in patients with GHD. The effectiveness of bone active drugs in the prevention of VFs in both clinical settings needs to be clarified.