Causes and Risks Calcium and phosphorus are important body minerals. They form the mineral component of bones, and they exist as charged particles called ions in the blood and inside cells. The parathyroid glands are located behind the thyroid gland in the neck.
Hypoparathyroidism is the clinical condition caused by a lack of parathyroid hormone.
Calcium levels in the blood fall, and phosphorus levels rise. Low blood calcium levels may cause symptoms such as tingling of the lips, fingers and toes, and muscle cramps, or spasms. 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. PTH secretion may be impaired when blood levels of the element magnesium are low or when blood pH is too high, a condition called metabolic alkalosis.