WHAT IS PARATHYROID HORMONE?

Parathyroid hormone (PTH) is responsible for regulating the levels of calcium and phosphate throughout the body. It is released from the four parathyroid glands, located around the thyroid gland in the neck.

When calcium levels are too low, PTH is released. It acts on the bones, kidneys and the intestine to restore normal calcium levels in the blood. The diagram below shows how PTH acts on the various areas of the body.

Kidneys – The kidneys are key in regulating mineral levels. PTH acts on the kidneys directly to increase the amount of calcium that is reabsorbed into the blood, and to increase the amount of phosphate that is excreted in the urine.
Bone – PTH stimulates the release of calcium and phosphate from the bones of the skeleton into the blood.
Gut – PTH triggers the conversion of vitamin D into the active form in the kidney. Active vitamin D acts in the gut to increase the amount of calcium and phosphate that is absorbed by the intestine.

About Hypoparathyroidism

Hypoparathyroidism (hypopara) is a rare disorder, where PTH levels in the body are low or completely absent. As a result, blood calcium and phosphate levels cannot be controlled.
Calcium is important for the normal functioning of all cells in the body, so if levels are uncontrolled, this can cause symptoms in all areas of the body.
If hypopara is left untreated, this results in blood calcium levels becoming too low, which is known as hypocalcaemia. Hypocalcaemia can cause symptoms of varying severity all over the body, but commonly affects the nerves and muscles.
Hypopara is usually treated with supplements of calcium and vitamin D, which increase calcium levels. In some cases, calcium levels can become too high, known as hypercalcaemia. This has a number of different symptoms, which are experienced throughout the body.

Hypopara is rare. Recent data collected in the United States shows that 24–37 individuals per 100,000 have the condition. This is estimated to be approximately 60,000–80,000 people in the United States, but in other countries the incidence is reported to be lower.
Overall, 75% of cases of hypopara are due to neck surgery, 75% of hypopara cases occur in women and 75% of hypopara cases occur in patients aged 45 years and older. See below for a chart of the major causes of hypopara.

Causes

Genetic Genetics account for less than 10% of all cases, although represent the leading cause of hypopara in children.

Autoimmune This occurs when the immune system attacks the parathyroid glands and causes PTH release to be reduced.

Radiotherapy Rarely, irradiation of the head and neck during cancer therapy, can damage the parathyroid gland and reduce PTH secretion.

Idiopathic Some cases of hypopara have unknown causes and are referred to as idiopathic.

Surgery This is the leading cause of hypopara. Approximately 75% of cases are caused by removal of or accidental damage to the parathyroid glands during neck surgery.

WHAT IS PARATHYROID HORMONE?

About Hypoparathyroidism

Causes

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WHAT IS PARATHYROID HORMONE?

About Hypoparathyroidism

Causes

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