is is an endocrine disorder in which the parathyroid glands in the neck do not produce enough parathyroid hormone (PTH). Common signs and symptoms include abdominal pain, brittle nails, cataracts, dry hair and skin, muscle cramps, tetany, pain in the face, legs, and feet, seizures, tingling sensation, and weakened tooth enamel (in children). It may be caused by injury to the parathyroid glands (e.g., during surgery). Other causes, include low blood magnesium levels, a side effect of radioactive iodine treatment for hyperthyroidism, metabolic alkalosis, DiGeorge syndrome, and type I polyglandular autoimmune syndrome. The goal of treatment is to restore the calcium and mineral balance in the body. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.