Hypoparathyroidism is caused by underactive parathyroid glands.
Underactive parathyroid glands produce too little parathyroid hormones, which in turn causes low levels of calcium in the blood stream. The low levels of calcium lead to tetany, an increased excitability of the nerves. Causes of parathyroidism include accidental removal of a parathyroid gland when the thyroid is removed, or when part of the parathyroid tissue is removed. Other causes include absent parathyroid glands from birth or the sudden stop of functioning due to unknown reasons. The following are the most common symptoms of hypoparathyroidism.