Causes

Hypoparathyroidism occurs when your parathyroid glands don't secrete enough parathyroid hormone. You have four small parathyroid glands in your neck behind your thyroid gland.

Factors that can cause hypoparathyroidism include:

• Neck surgery. This most common cause of hypoparathyroidism develops after accidental damage to or removal of the parathyroid glands during surgery. Neck surgery may be done to treat conditions of the thyroid gland, or to treat throat or neck cancer.
• Autoimmune disease. In some cases, your immune system attacks parathyroid tissues as if they were foreign bodies. In the process, the parathyroid glands stop producing their hormone.
• Hereditary hypoparathyroidism. In this form, either you're born without parathyroid glands or they don't work properly. Some types of hereditary hypoparathyroidism are associated with deficiencies of other hormone-producing glands.
• Low levels of magnesium in your blood. Low magnesium levels can affect the function of your parathyroid glands. Normal magnesium levels are required for normal production of parathyroid hormone.
• Extensive cancer radiation treatment of your face or neck. Radiation can result in destruction of your parathyroid glands. In rare cases, radioactive iodine treatment for hyperthyroidism may lead to hypoparathyroidism.