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Hypoparathyroidism

By

James L. Lewis III

, MD, Brookwood Baptist Health and Saint Vincent’s Ascension Health, Birmingham

Last full review/revision Jul 2021| Content last modified Jul 2021

Hypoparathyroidism is a deficiency of parathyroid hormone (PTH) often caused by an autoimmune disorder, treatment-related damage to the parathyroid glands, or removal of the glands during surgery.

(See also Overview of Parathyroid Function.)

  • Symptoms of hypoparathyroidism are due to low calcium levels in the blood and include tingling in the hands or around the mouth and muscle cramps.
  • Blood tests to check the levels of parathyroid hormone and calcium are needed for diagnosis.
  • People are given vitamin D and calcium to treat hypoparathyroidism.

The parathyroid glands are located near the thyroid gland. Their exact location, and even the total number of glands, is quite variable. These glands secrete parathyroid hormone (PTH), which regulates calcium levels in the blood and tissues through its effects on bones, the kidneys, and the intestine.

Hypoparathyroidism results from deficient parathyroid hormone (PTH) secretion, which can occur as the result of

  • Removal of or damage to several parathyroid glands during surgery to remove them (parathyroidectomy) or the thyroid gland (thyroidectomy)
  • An inherited autoimmune disorder (a malfunction of the body's immune system that causes the body to attack its own tissues)
  • An inherited disorder in which the parathyroid glands are missing or shrunken

The Parathyroid Glands

The Parathyroid Glands

Postoperative hypoparathyroidism

Postoperative hypoparathyroidism is a common and usually temporary condition that occurs after partial removal of the thyroid gland (subtotal thyroidectomy). Permanent hypoparathyroidism occurs after less than about 3% of subtotal thyroidectomies. People usually develop hypocalcemia (low calcium level in the blood) about 24 to 48 hours after surgery, but hypocalcemia may occur months or years later.

PTH deficiency is more common after complete removal of the thyroid gland (such as to treat thyroid cancer) or after surgery to remove overactive parathyroid glands. Even if all the parathyroid glands are not removed or a small piece of normal gland is reimplanted in a muscle (subtotal parathyroidectomy), severe hypocalcemia may occur. Risk factors for severe hypocalcemia after subtotal parathyroidectomy include

Inherited hypoparathyroidism

Some people have an inherited condition in which their parathyroid glands are absent or underdeveloped. Other people inherit a tendency for their immune system to attack their parathyroid glands (and sometimes other glands).

Pseudohypoparathyroidism

Pseudohypoparathyroidism is an uncommon group of inherited disorders that resemble true hypoparathyroidism except that they are caused by the resistance of target organs to the effects of PTH rather than a deficiency of PTH. There are several types of pseudohypoparathyroidism, each of which has a different and complicated genetic cause.

Symptoms

Symptoms of hypoparathyroidism are due to hypocalcemia and include tingling in the hands or around the mouth and muscle cramps. In severe cases, tetany occurs. Tetany is periodic painful muscle spasms.

Diagnosis

  • Blood tests to measure parathyroid hormone (PTH) and calcium levels

People with hypoparathyroidism have hypocalcemia (low level of calcium in the blood) and hyperphosphatemia (high level of phosphate in the blood). Because hypocalcemia prompts increased PTH secretion, the level of PTH in the blood should go up in response to hypocalcemia. Thus, in people with hypocalcemia, doctors can make a diagnosis based on the following blood test results:

  • Low or even low-normal PTH levels are inappropriate and suggest hypoparathyroidism.
  • Undetectable PTH levels suggest idiopathic hypoparathyroidism.
  • High PTH levels suggest pseudohypoparathyroidism or an abnormality of vitamin D metabolism.

Treatment

  • Calcium and vitamin D

Taking calcium and vitamin D supplements by mouth may be sufficient for people with postoperative hypoparathyroidism.

Sometimes intravenous calcium is needed.

If the hypoparathyroidism does not respond adequately to calcium and vitamin D supplements, the doctor may prescribe treatment with recombinant parathyroid hormone. Recombinant parathyroid hormone may decrease the risk of long-term complications of hypoparathyroidism, such as hypercalciuria and decreased bone mineral density, and lower the doses of calcium and vitamin D needed. Doctors monitor the person's blood levels of calcium and phosphate and may need to increase or decrease the dose of recombinant parathyroid hormone.

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