Hypoparathyroidism and other causes of hypocalcemia

Hypoparathyroidism is a rare disorder most commonly caused by anterior neck surgery. Other causes include autoimmunity, iron or copper overload syndromes, metastatic infiltration of the parathyroid glands, ionizing radiation, and genetic familial causes including isolated or syndromic forms of hypoparathyroidism. Hypoparathyroidism is one of many causes of hypocalcemia. The differential diagnosis of hypocalcemia also includes PTH resistance, hypovitaminosis D from many causes, vitamin D resistance leading to rickets or osteomalacia, and a long list of divergent other causes. Regardless of the cause of hypocalcemia, symptoms usually include neuromuscular irritability leading to fingertip or toe tip tingling or numbness, muscle cramps, or tetany, but more severe forms may cause a spectrum of symptoms including bronchospasm, laryngospasm, seizures, cardiac rhythm disturbances, or sudden death. Signs of hypocalcemia include Chvostek’s and Trousseau’s signs, QTc interval prolongation, and brain and other soft tissue calcification. Treatment of hypocalcemia typically involves supplementation with calcium and vitamin D in different forms. Some patients benefit from supplementation with magnesium, thiazide-type diuretics, or parathyroid hormone analogues.