Parathyroid glands are small peas sized glands of the endocrine system which are located behind the thyroid. Occasionally the parathyroid glands are located in unusual places (ectopic locations) such as inside the thyroid gland, in the chest, in the thymus gland or near the jaw. Most people have four parathyroid glands but occasionally a person is born with three or five of them.
Functions of the Parathyroid Glands
The parathyroid glands are separate from the thyroid gland and produce parathyroid (PTH) hormone, parathyroid hormone that regulates the level of calcium and phosphorous in the blood. Calcium is important to good bone health as well as for the function of most cells in the body including nerve and muscle cells. Phosphorous is a mineral important to all the body's tissues. Parathyroid hormone regulates release of calcium from the bone, the excretion of calcium and phosphorous in the urine and the absorption of calcium from the intestines.
When the blood calcium falls, the parathyroid gland increases the amount of parathyroid hormone released in turn increasing the calcium to maintain a very fine balance. The single major disease of parathyroid glands is over activity of one or more of the parathyroids which make too much parathyroid hormone causing hypercalcemia, a potentially serious calcium imbalance. This disease is called hyperparathyroidism.
The only role of the parathyroid in the human body is to regulate the levels of calcium in the bloodstream. Indirectly, therefore, the parathyroid glands, working in unison in a normal situation, determine the strength and integrity of the bones. Overactive parathyroid glands can cause a number of symptoms most common of which are Osteoporosis or Osteopenia. This occurs when too much calcium is leached from the bones.