There are four parathyroid glands in humans located behind the thyroid gland. Very rarely, they can be located in other areas of the neck or in the chest. Many a times, parathyroid glands are confused with thyroid gland and its function. Parathyroid hormone has no relation with thyroid hormone production or the function of thyroid hormone except they are neighbors and good friends. The most important work of all these four parathyroid glands is to maintain calcium, an important element in our body by secreting a hormone called Parathyroid hormone (PTH).

Calcium is needed for our nervous system, muscle functions and keeping our bones strong and this is the only element which has its own regulatory check in the form of PTH. If the calcium levels are high in the body, the parathyroid gland makes less PTH and similarly if the calcium levels are low then more PTH is made in order to maintain a normal calcium balance.

The main medical problem that arises from these glands is called hyperparathyroidism (where PTH production is more). Usually, one of the four glands enlarges in size (from rice grain size to pea, olive or walnut size) and over produces PTH hormone. When PTH is over secreted, the calcium levels also increase in blood. This calcium increase in turn causes various problems like weakness of bones, fractures, depression, changes in behavior, tiredness, lethargy and kidney stones etc. This can be identified easily with a simple blood test called calcium and PTH. The primary treatment of this condition is operation and removal of the abnormal parathyroid gland/s. All the four glands do the same exact function and removal of one gland will not lead to any major problem. In fact, only one half of a single parathyroid gland is enough for calcium maintenance and function.

PTH may also rise in a rare cancer of thyroid gland. In this disease which is known as Multiple Endocrine Neoplasia type 2A (MEN2A), some endocrine glands are enlarged and produce excess hormones from them. There is Medullary Cancer of Thyroid (leading to excess production of Calcitonin), Pheochromocytoma of Adrenal Glands (leading to excess production of Adrenaline/Noradrenaline) and Parathyroid adenoma (leading to excess production of PTH). Operation is the only chance of cure in this disease.

The other medical condition that we see is called hypoparathyroidism (less PTH). This is the exact opposite of the above written problem where in the calcium level becomes low due to low PTH production. This can happen after operations on thyroid (as normal parathyroid glands can be damaged during that operation) or because of some other autoimmune diseases. This can be managed by giving tablets of vitamin D and calcium.

PTH level will also increase when there is vitamin D deficiency which is a very common condition in clinical practice. This is called secondary hyperparathyroidism. In this setting the calcium will be normal or low and never be high. This is completely different from the above mentioned hyperparathyroidism where PTH and calcium both are high.

If you have any concerns or questions about your calcium, PTH and vitamin D, contact us.

This page is edited by Dr. Sruti Chandrasekaran who is an expert Endocrinologist. Dr Sruti is currently working as Consultant Endocrinology at Global Hospitals, Chennai (India).

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