Also Known As
Parathyroid Cancer
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This article waslast modified on July 3, 2018.
What are the parathyroids and parathyroid diseases?

The parathyroid glands are four (in most people) button-sized glands that are located near the thyroid gland at the base of the throat. Each parathyroid gland produces parathyroid hormone (PTH), which helps to regulate the amount of calcium in the blood.

Calcium is a mineral that is essential for the proper functioning of muscles, nerves, and the heart and is required in blood clotting and in the formation of bones. About 99% of calcium is found in the teeth and bones while most of the remaining 1% circulates in the blood. Some calcium is lost from the body every day, filtered from the blood by the kidneys and excreted into the urine.

To regulate blood calcium, PTH functions as part of a feedback system that involves calcium, phosphorus (as phosphate), and vitamin D. Phosphorus is another mineral that works with calcium in its different functions in the body. Most of it binds with calcium to help form bones and teeth. Vitamin D promotes the absorption of calcium in the intestines.

The role of the parathyroid glands is to ensure that the concentration of calcium in blood remains within a fairly narrow range. As the level of calcium in the blood drops, the parathyroid glands produce and release PTH, which works in three ways to boost calcium in the blood:

  • PTH acts on the kidneys to reduce the excretion of calcium in urine and to promote the elimination of phosphate in the urine.
  • It stimulates the kidneys to convert vitamin D from the inactive to the active form. This in turn increases the amount of calcium absorbed from food in the intestines.
  • It promotes the release of calcium from bones into the bloodstream.

As the level of calcium in the blood increases, the production of PTH by the parathyroid glands falls. This feedback system normally maintains a dynamic but relatively stable concentration of calcium in the blood.

Parathyroid diseases are conditions that affect the amount of parathyroid hormone (PTH) that is produced, which in turn affects the concentration of calcium in the blood.

Accordion Title
About parathyroid disease
  • Types

    Hyperparathyroidism refers to the production of too much PTH by the parathyroid glands. It is classified as primary, secondary, or tertiary:

    • Primary hyperparathyroidism is a condition in which there is a problem with the parathyroid glands themselves. A person with primary hyperparathyroidism has too much PTH and too much calcium in the blood. Since calcium is pulled from the bones, the bones weaken over time, increasing the risk of fractures.

      About 85% of the time, primary hyperparathyroidism is due to an adenoma (benign tumor) in a single parathyroid gland. Less commonly, it is due to multiple adenomas or to hyperplasia, an increase in the size and activity of all of the parathyroid glands. Very rarely (about 1% of the time), it is due to parathyroid cancer, as tumors can produce excess PTH.

      About 100,000 people in the United States develop primary hyperparathyroidism each year. It is seen most frequently in people over 50 years old and occurs more often in women than men. In rare cases, it is linked to an inherited endocrine syndrome (MEN 1 or MEN 2).

    • Secondary hyperparathyroidism is usually due to insufficient amounts of calcium in blood, which may occur in the following conditions:
      • Kidney failure; this can cause increased phosphate and lowered levels of the active form of vitamin D, which lead to increased PTH production.
      • Vitamin D deficiency
      • Calcium malabsorption caused by gastrointestinal disorders, for example
    • Tertiary hyperparathyroidism occurs rarely when the underlying cause of secondary hyperparathyroidism is resolved, but the parathyroid glands continue to produce excess PTH.

    Hypoparathyroidism refers to a deficiency of PTH and can be persistent or temporary. This condition does not occur as frequently as hyperparathyroidism. Regardless of the cause, those affected by hypoparathyroidism have decreased blood calcium that may range from mild to severe.

    • The most common cause is the removal of the parathyroid glands during surgery. This might occur when a person is being treated for thyroid cancer or cancer of the throat and the thyroid gland is removed. Surgery is also done to treat hyperparathyroidism that is due to hyperplasia. Three or 3.5 of the glands are typically removed and the remaining gland or gland portion may be autotransplanted (moved) to the person's neck or forearm. If the remaining gland does not function adequately, hypoparathyroidism may result.
    • Sometimes, it is due to damage to all of the glands by an autoimmune disorder.
    • Rarely, it is due to a failure of the glands to develop properly.
    • Temporary hypoparathyroidism may be seen after treatment for hyperparathyroidism. This occurs as "hungry bone syndrome" when PTH decreases suddenly and the bones take calcium from the blood. It also can be seen after birth in newborns whose mothers have hyperparathyroidism.
  • Signs and Symptoms

    The signs and symptoms of parathyroid disease are associated with the effects of a persistently high blood calcium level (hypercalcemia) or low calcium blood level (hypocalcemia). Some examples include:

    High calcium:

    • Fatigue
    • Nausea, loss of appetite, abdominal pain
    • Excessive thirst
    • Excessive urination
    • Bone pain and fragile bones
    • Kidney stones (excess calcium in the urine can crystalize and form stones)
    • Constipation
    • Depression

    Low calcium:

    • Abdominal pain
    • Muscle cramps
    • Tingling sensations, numbness in the fingers

    Many individuals with parathyroid disease are diagnosed at an early stage with few or no symptoms, but others may experience moderate to severe symptoms before seeing a health care provider.

  • Tests

    Testing is performed to detect, diagnose, and monitor parathyroid diseases. The first indication of parathyroid disease may be an abnormal calcium result on a set of routine blood tests (such as a comprehensive metabolic panel, CMP). The tests used to evaluate the parathyroid glands are listed below.

    Laboratory tests

    • Calcium – to determine whether the level is normal, elevated, or low
    • Phosphate – to evaluate levels in conjunction with calcium results
    • Urine calcium – to evaluate the amount of calcium that is being excreted by the kidneys
    • Parathyroid hormone (PTH) – measured with calcium to determine if the body is responding appropriately
    • Vitamin D – to see whether a deficiency in vitamin D may be affecting the calcium level

    Non-laboratory tests

    • Ultrasound – an imaging scan that can help locate parathyroid glands and evaluate their size
    • Sestamibi scan – a test that uses two radioactive compounds to identify parathyroid glands that have a benign growth (adenoma), hyperplasia, or cancer
    • MRI or CT scan – sometimes used to help locate abnormal parathyroid glands or cancer
    • Bone mineral density test (bone densitometry) – used to evaluate bone density
    • Abdominal X-ray or CT scan – used to identify and locate kidney stones, which can form when there is an excess of calcium in the urine
  • Treatment

    The treatment for primary hyperparathyroidism is surgery. If a person has a benign growth (adenoma), the affected parathyroid gland is removed. If a person has hyperplasia, then 3 to 3.5 parathyroid glands are usually removed and the remaining gland or portion of a gland may be transplanted to a person's forearm. Parathyroid cancer is also treated through surgery.

    For secondary hyperparathyroidism, it is important to treat the underlying condition, which is most often kidney disease.

    In some cases, medication may be used to reduce PTH secretion and/or high calcium levels in blood.

    Patients with hypoparathyroidism are treated with calcium and vitamin D supplementation. If it is due to a temporary condition, such as "hungry bones" or a newborn whose mother had hyperparathyroidism, then monitoring of calcium levels may be required until the situation resolves.

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

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