Parathyroid hormone and analogs (a synthetic form of parathyroid hormone) control the distribution of phosphate and calcium in the body. High levels of parathyroid hormone triggers transfer of calcium from the bones to the blood. It increases absorption of calcium by the intestine and increases reabsorption of calcium by the renal tubules. A low level of parathyroid hormone reduces calcium levels in the blood.
Constant high levels of parathyroid hormone cause bone resorption but sporadic administration of exogenous recombinant parathyroid hormone stimulates bone formation.
Clinically used parathyroid hormone analogs are used to build bone mass in patients who have low bone density. They are used to treat or prevent osteoporosis in men and postmenopausal women, who have fractures or are at a high risk of having fractures.