Parathyroid hormone (PTH) is a parathyroid-secreted polypeptide hormone that increases the level of calcium in blood by enhancing calcium mobilization from bone, increasing the calcium:phosphate ratio in the kidney and promoting the absorption of calcium by the intestines. PTH is an anabolic agent that improves osteoblastic bone development. PTH 1-34 induces bone morphogenetic protein (BMP) gene transcription. Active N-terminal fragment of PTH (residues 1–34), has been used as a therapeutic for postmenopausal women with osteoporosis who are at high risk for fracture.