Parathyroid hyperplasia is the enlargement of all four parathyroid glands. The parathyroid glands are four glands in the neck that produce parathyroid hormone (PTH).

Parathyroid hyperplasia may occur sporadically (in persons without a family history of the disease) or as part of three inherited syndromes: multiple endocrine neoplasia I (MEN I), MEN IIA, and isolated familial hyperparathyroidism.

In the familial syndromes, a mutated gene is passed down in an autosomal dominant fashion. That means you only need to get the gene from one parent to develop the condition.

In MEN I, the problems in the parathyroids are associated with other tumors in the pituitary and the pancreas. In MEN IIA, the overactivity of the parathyroids is associated with tumors in the adrenal gland or thyroid. See the specific articles for more information on the causes of these syndromes.

Symptoms may include:

• Bone fractures
• Constipation
• Kidney stones
• Lethargy
• Muscle pain
• Nausea

Blood tests will be done to check calcium, phosphorus, chloride, bicarbonate, and PTH levels. A 24-hour urine test is done to determine how much calcium is being removed from the body.

Bone x-rays and a bone density test can help detect fractures, bone loss, and bone softening.

Surgery is the preferred treatment. Usually 3 1/2 glands are removed. The remaining tissue may be implanted in the forearm so a doctor can easily operate on it if symptoms come back. This tissue will also help the body control calcium levels.

Increased calcium levels persist or return about 20% of the time after surgery.

Parathyroid hyperplasia causes about 15% of cases of hyperparathyroidism, which leads to an increase in blood calcium levels.

Complications include increased calcium in the kidneys and osteitis fibrosa cystica.

Patients may also have complications from the other endocrine tumors that are part of the multiple endocrine neoplasia syndromes. See: MEN I and MEN IIA

Call your health care provider if you have any symptoms of hypercalcemia, or there is a family history of any of the MEN syndromes.

Patients with a family history of the MEN may have genetic screening to check for the defective gene. Those who have the defective gene may have routine screening tests to detect any early symptoms.

Wysolmerski JJ, Insogna KL. The parathyroid glands, hypercalcemia, and hypocalcemia. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008:chap. 266.

Bringhurst FR, Demay MB, Kronenberg HM. Disorders of mineral metabolism. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008:chap. 27.