Unlike the thyroid, the parathyroid is less known. In most cases, this organ comprises four separate glands which are situated behind the thyroid gland.
The sole purpose of the parathyroid glands is to regulate the metabolism of calcium in the body by secreting the parathyroid hormone (PTH). As is known, calcium is the main structural component of bones and teeth and is an important element for the muscular system, nervous system, and for other processes in the body.
As is the case with the thyroid gland, the parathyroid can produce too much parathyroid hormone (hyperparathyroidism), or too little parathyroid hormone (hypoparathyroidism). An excess of parathyroid hormone has a damaging effect since it results in the release of too much calcium into the blood stream. Since parathyroid gland disease was first described, the symptoms have become known as "moans, groans, stones, and bones...with psychic overtones".
A lack of parathyroid hormones (hypoparathyroidism} leads to low blood calcium (hypocalcemia) and can cause muscle irritability and spasms (tetany).
A dysfunction of the parathyroid gland can either be treated with medications which regulate the hormonal metabolism, or surgical intervention is required. In some cases, the complete removal of the parathyroid becomes necessary. To maintain the calcium metabolism, a part of a parathyroid gland is frequently replanted in another part of the body.