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Hypoparathyroidism is a clinical state produced by failure to secrete parathyroid hormone (PTH) and resulting hypocalcemia. It is most commonly seen after thyroidectomy or surgery for primary hyperparathyroidism. Less often, it may be idiopathic, familial, or result from a congenital absence of the parathyroid glands (DiGeorge's syndrome) patients often have antibodies against the parathyroid and other tissues. Autoimmunity may play a role in idiopathic hypoparathyroidism. Hypoadrenalism and mucocutaneous candidiasis may accompany familial cases of hypoparathyroidism. Other causes include previous irradiation of the neck, magnesium deficiency, metastatic neoplasms, and infiltrative diseases. Clinical features are primarily caused by hypocalcemia..

Signs and symptoms of hypoparathyroidism can vary depending on the duration of hypocalcemia. Although some patients remain asymptomatic, most exhibit signs of hypocalcemia, including tetany, carpopedal spasm, paresthesias of the lips and hands, and a positive Chvostek's sign (twitching of the facial muscles when tapped on the facial nerve near the parotid gland). Carpal spasm may be spontaneous or induced.

Hypoparathyroidism can also occur in combination with other endocrine abnormalities, such as Addison's disease, pernicious anemia, and celiac sprue. It is important to differentiate hypoparathyroidism from syndromes that involve malabsorption of calcium, vitamin D, or magnesium. Certain drugs may produce hypocalcemia, e.g., loop diuretics, phenytoin (Dilantin), plicamycin [mithramycin](Mithracin), and large doses of rectal phosphate preparations. The destruction of lymphomas or leukemias after treatment may also result in clinical hypocalcemia. Hypocalcemia may be seen with rapid expansion of intravascular volume or chelation resulting from transfusions of large volumes of citrated blood products. Hypocalcemia may be associated with acute pancreatitis and certain metastatic carcinomas, e.g., breast cancer and prostate cancer that metastasize to the bone. Lastly, transient hypocalcemia is commonly seen after parathyroidectomy for hyperparathyroidism.


Pseudohypoparathyroidism is a rare genetic defect characterized by normal to increased PTH levels and target-organ unresponsiveness. Although the parathyroid glands are present and often hyperplastic, hypocalcemia and hyperphosphatemia exist despite elevated PTH. Defects in PTH receptors or other postreceptor abnormalities are suspected causes of this disease. Patients exhibit characteristic features, including round facies, short stature, dental hypoplasia, bony exostoses, brachydactyly (shortening of metatarsal and metacarpal bones), mental retardation, and heterotopic calcifications. Occasionally, tissue resistance to the actions of TSH, glucagon, and vasopressin may be present. Treatment for pseudohypoparathyroidism follows the same guidelines.