thyroid anatomy

What is the parathyroid and parathyroid adenoma?

Parathyroid glands are located in your neck, next to the thyroid gland. Most people have four pea-sized, oval-shaped parathyroid glands. The job of the parathyroid is to secrete parathyroid hormone, which helps regulate how the body uses calcium.

Calcium is needed by cells in many parts of your body: the brain, heart, nerves, bones and digestive system. Parathyroid hormone takes calcium from bone, where it's stored, and releases it into the blood stream. "Communication" between the parathyroid and blood stream help keep calcium at its normal level.

Sometimes, benign (noncancerous) growths called adenomas appear on one or more of a person's parathyroid glands. We don’t know the cause of most parathyroid adenomas. About 10% are thought to be hereditary (inherited in a family). Radiation exposure to the head and neck area that the patient had as a child or an young adult also may increase the risk of adenomas. Parathyroid cancer is extremely rare and occurs in less than 1% of all parathyroid cases.

Adenomas cause the parathyroid gland to make more parathyroid hormone than the body needs, a condition called primary hyperparathyroidism. Too much parathyroid hormone upsets the body's normal calcium balance, which increases the amount of calcium in the blood stream.

A similar but less common condition, called secondary hyperparathyroidism, can occur in people with chronic kidney failure.

Who develops parathyroid adenoma?

Approximately 100,000 Americans develop primary hyperparathyroidism each year. Women are twice as likely to develop parathyroid adenomas as men, and often after menopause. Primary hyperparathyroidism may be caused by one adenoma, more than one adenoma (hyperplasia), or cancer (which is very rare).

What are the symptoms of parathyroid adenoma?

Too much calcium in the blood (hypercalcemia) can cause a number of symptoms and medical conditions. These include:

Many patients may believe they don't have any symptoms. However, when the calcium levels have been high for a number of years, patients may not be able to tell whether symptoms exist.

Last reviewed by a Cleveland Clinic medical professional on 03/19/2015.


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  • National Institute of Diabetes and Digestive and Kidney Disease. Primary Hyperparathyroidism. Accessed 10/16/2019.
  • American Family Physician. Hyperparathyroidism. Accessed 10/16/2019.
  • Wieneke JA, Smith A. Parathyroid adenoma. Head Neck Pathol. 2008;2(4):305–308. doi:10.1007/s12105-008-0088-8

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