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Definition Return to top
Hypoparthyroidism is a deficiency of parathyroid hormone that causes abnormal metabolism of calcium and phosphorus.
Causes, incidence, and risk factors Return to top
Calcium and phosphorus are important body minerals. They form the mineral component of bones, and they exist as charged particles called ions in the blood and inside cells.
Parathyroid hormone (PTH) regulates the amount of calcium and phosphorus in bone and blood. The four small parathyroid glands located in the neck, behind the thyroid, make PTH.
Hypoparathyroidism is the clinical condition caused by a lack of PTH. Blood calcium levels fall, and phosphorus levels rise. Low blood calcium levels may cause symptoms such as tingling of the lips, fingers, and toes, and muscle cramps or spasms.
The most common cause of hypoparathyroidism is injury to the parathyroid glands during head and neck surgery. Rarely, hypoparathyroidism is a side effect of radioactive iodine treatment for hyperthyroidism. PTH secretion may be impaired when blood levels of magnesium are low or when blood pH is too high, a condition called metabolic alkalosis.
DiGeorge syndrome is a childhood disease in which hypoparathyroidism occurs due to congenital absence of the parathyroid glands. Familial hypoparathyroidism occurs with other endocrine diseases such as adrenal insufficiency in a syndrome called type I polyglandular autoimmune syndrome (PGA I).
Risk factors for hypoparathyroidism include recent thyroid or neck surgery, family history of parathyroid disorder, or history of certain autoimmune endocrine diseases such as Addison's disease. The incidence is about 4 out of 100,000 people.
Symptoms Return to top
Additional symptoms that may be associated with this disease:
Signs and tests Return to top
Treatment Return to top
The goal of treatment is to restore the calcium and associated mineral balance within the body.
Oral calcium carbonate and vitamin D supplements are usually life-long therapy. Blood levels require periodic monitoring to ensure proper dosage. A high-calcium, low-phosphorous diet is recommended.
Supportive care is necessary for an acute life-threatening attack or hypoparathyroid tetany (prolonged muscle contractions). Calcium is administered by intravenous (IV)infusion. Precautions are taken to prevent seizures or larynx spasms. Heart monitoring for abnormal rhythms is continued until the person is stabilized. When the life-threatening attack has been controlled, treatment continues with oral preparations.
Expectations (prognosis) Return to top
The probable outcome is good if the diagnosis is made early. However, dental changes, cataracts, and brain calcifications are irreversible.Complications Return to top
Calling your health care provider Return to top
Call your health care provider if symptoms of hypoparathyroidism develop.Prevention Return to top
If you undergo thyroid or neck surgery, be watchful for early signs of hypoparathyroidism so that treatment with calcium and vitamin D supplements can be started promptly.
Update Date: 1/6/2003 Updated by: Todd T. Brown, M.D., Division of Endocrinology and Metabolism, Johns Hopkins Hospital, Baltimore, MD. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |