Position paper on the indications for the use of parathyroid hormone (PTH 1-34) in the treatment of osteoporosis

Abstract

Parathyroid hormone (PTH) is a peptide hormone secreted by the parathyroid glands which, amongst many varied physiological effects, serves to maintain normal serum calcium levels. In fulfilling this function, the hormone interacts with parathyroid receptors in a number of tissues, including bone. One effect in bone is to stimulate pre-osteoblast formation and differentiation to mature functional osteoblasts and to prevent their apoptosis. Cytokines subsequently released by the osteoblasts then stimulate osteclastic activity, bone breakdown and release of calcium into the circulation. Continued high level exposure of bone to PTH will result in eventual bone loss, but intermittent exposure will have an anabolic effect — fact which makes this peptide useful as a potent treatment for osteoporosis. Teriparatide is a 34 amino acid peptide which mimics the physiological effects of PTH and is registered in South Africa for the treatment of established osteoporosis with or without vertebral fractures in post menopausal women and in men.1 The intact human recombinant molecule PTH (1-84) is not available in South Africa and will not therefore be included in this discussion.