Hypoparathyroidism

Definition

Hypoparathyroidism is is an endocrine disorder in which the parathyroid glands in the neck do not produce enough parathyroid hormone (PTH).

See also: Hyperparathyroidism

Causes, incidence, and risk factors

The parathyroid glands help control calcium use and removal by the body. They do this by producing parathyroid hormone, or PTH. PTH helps control calcium, phosphorus, and vitamin D levels within the blood and bone.

Hypoparathyroidism occurs when the glands produce too little PTH. Blood calcium levels fall, and phosphorus levels rise.

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.

Hypothyroidism may also be caused by

• Low blood magnesium levels
• Metabolic alkalosis

DiGeorge syndrome is a childhood disease in which hypoparathyroidism occurs because all the parathyroid glands are missing at birth. Familial hypoparathyroidism occurs with other endocrine diseases, such as adrenal insufficiency, in a syndrome called type I polyglandular autoimmune syndrome (PGA I).

The risk factors for hypoparathyroidism include recent thyroid or neck surgery, a family history of parathyroid disorder, or certain autoimmune diseases such as Addison's disease.

Symptoms

• Abdominal pain
• Brittle nails
• Cataracts
• Dry hair
• Dry, scaly skin
• Muscle cramps
• Muscle spasms called tetany (can affect the larynx, causing breathing difficulties)
• Pain in the face, legs, and feet
• Seizures
• Tingling lips, fingers, and toes
• Weakened tooth enamel (in children)

Additional symptoms may include:

• Decreased consciousness
• Delayed or absent tooth formation
• Hand or foot spasms
• Painful menstruation

Signs and tests

Blood tests will be done to check calcium, phosphorus, magnesium, and PTH levels. An ECG may show abnormal heart rhythms.

A urine test may be done to determine how much calcium is being removed from the body.

Treatment

The goal of treatment is to restore the calcium and mineral balance in the body.

Treatment involves calcium carbonate and vitamin D supplements, which usually must be taken for life. Blood levels are measured regularly to make sure that the dose is correct. A high-calcium, low-phosphorous diet is recommended.

Persons who have life-threatening attacks of low calcium levels or prolonged muscle contractions are given calcium through a vein (IV). Precautions are taken to prevent seizures or larynx spasms. The heart is monitored for abnormal rhythms until the person is stable. When the life-threatening attack has been controlled, treatment continues with medicine taken by mouth.

Expectations (prognosis)

The outcome is likely to be good if the diagnosis is made early. However, changes in the teeth, the development of cataracts, and brain calcifications are irreversible.

Complications

Hypoparathyroidism in children may lead to stunted growth, malformed teeth, and slow mental development.

Overtreatment with vitamin D and calcium can cause hypercalcemia (high blood calcium) and may sometimes interfere with kidney function.

Hypoparathyroidism increases your risk of pernicious anemia, Addison's disease, cataracts, and Parkinson's disease.

Calling your health care provider

Call your health care provider if you develop any symptoms of hypoparathyroidism.

Seizures or breathing problems are an emergency. Call 911 or your local emergency number immediately.

References

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.