Where is pth synthesized

It is usually treated medically with oral calcium and vitamin D analogues but the availability of parathyroid hormone replacement therapy may change the approach to treatment for some patients. About Contact Events News. Search Search. You and Your Hormones. Students Teachers Patients Browse. Human body. Home Hormones Parathyroid hormone. Parathyroid hormone Parathyroid hormone is secreted by the parathyroid glands and is the most important regulator of blood calcium levels.

Alternative names for parathyroid hormone PTH; parathormone; parathyrin What is parathyroid hormone? Peptide YY. Related Endocrine Conditions. Osteoporosis Primary hyperparathyroidism Secondary hyperparathyroidism Tertiary hyperparathyroidism Hypoparathyroidism Hypercalcaemia Hypocalcaemia View all Endocrine conditions.

Related Hormones. Calcitonin Vitamin D View all Hormones. Related Glands. Addition information on how parathyroid hormone and vitamin D control calcium balance can be found in the section Endocrine Control of Calcium Homeostasis. Parathyroid hormone is released in response to low extracellular concentrations of free calcium. Changes in blood phosphate concentration can be associated with changes in parathyroid hormone secretion, but this appears to be an indirect effect and phosphate per se is not a significant regulator of this hormone.

When calcium concentrations fall below the normal range, there is a steep increase in secretion of parathyroid hormone. Low levels of the hormone are secreted even when blood calcium levels are high. The figure to the right depicts parathyroid hormone release from cells cultured in vitro in differing concentrations of calcium. The parathyroid cell monitors extracellular free calcium concentration via an integral membrane protein that functions as a calcium-sensing receptor. Both increased and decreased secretion of parathyroid hormone are recognized as causes of serious disease in man and animals.

There is no doubt that chronic secretion or continuous infusion of parathyroid hormone leads to decalcification of bone and loss of bone mass. However, in certain situations, treatment with parathyroid hormone can actually stimulate an increase in bone mass and bone strength.

This seemingly paradoxical effect occurs when the hormone is administered in pulses e. Inadequate production of parathyroid hormone - hypoparathyroidism - typically results in decreased concentrations of calcium and increased concentrations of phosphorus in blood.