Mechanism and efficacy of parathyroid hormone in osteoporosis

Abstract

Background: Parathyroid hormone (PTH) and teriparatide, which is a PTH analog, are special options of osteoanabolic therapies for osteoporosis treatment. Their efficacy in improving the bone mineral density (BMD) and reducing fracture risk is considered to have a long-awaited justification.Current Concepts: PTH is an 84-amino acid polypeptide that plays a key role in the calcium homeostasis of the human body. It yields anabolic effects on the bone by intermittent injections. During the first 6 months of PTH treatment, bone formation increases rapidly and bone resorption rises gradually. PTH is believed to be maximally anabolic during the anabolic window. In the phase III trial of teriparatide, significant reductions in vertebral and non-vertebral fractures were identified. Teriparatide has been studied in drug-induced osteoporosis, postmenopausal women with osteoporosis, and men with osteoporosis. The data derived from clinical trials with teriparatide showed an increase of the BMD in the treatment group compared to that of the placebo. Selective advantages on fracture healing have been shown in some studies; however, consensus on the relationship between teriparatide and bone healing is unclear.Discussion and Conclusion: Teriparatide has been approved for osteoporosis treatment in various situations, including postmenopausal women, men with osteoporosis, and cases with glucocorticoid-induced osteoporosis. Additionally, it can be useful in high risk for fracture groups, if fractures persist despite bone resorption inhibitor therapy, and if bone resorption inhibitor administration is difficult and contraindicated.