The four parathyroid glands produce a hormone that regulates levels of calcium in the blood. Underactivity of the glands (hypoparathyroidism) causes low blood calcium, producing symptoms such as tingling, muscle spasms, and sometimes seizures (fits).
Hypoparathyroidism may be due to accidental damage during surgery or the immune system mistakenly attacking parathyroid tissue.
Treatment is with calcium and vitamin D supplements. Overactivity of the parathyroids (hyperparathyroidism) causes high blood calcium.
Symptoms may include depression, tiredness, excessive urination, weakness, confusion and, in severe cases, unconsciousness.
The high calcium levels may also cause kidney stones. Hyperparathyroidism may be caused by a benign tumor in one of the glands or may be due to another disorder, such as kidney disease.
Treatment is with surgery or medication, or of the underlying cause.