Hyperparathyroidism occurs when there is an overproduction of the parathyroid hormone (PTH) by one or more pdf the four parathyroid glands situated in the neck. PTH helps the body maintain the correct level of calcium in the bloodstream and in tissues. 

There are two varieties of hyperparathyroidism: primary hyperparathyroidism is the enlargement of the one or more glands, which causes overproduction of PTH and high calcium levels in the blood; and secondary hyperparathyroidism, which occurs as a result of another disease or condition. 

Symptoms of hyperparathyroidism can be mild or severe, but generally appear when high calcium levels cause damage to tissues, organs, or bones. Symptoms may include osteoporosis, kidney stones, abdominal pain, excessive urination, weakness, tiring easily, depression, bone or joint pain, nausea, vomiting, and a lack of appetite.

Treatment of hyperparathyroidism usually involves medication to balance calcium and PTH levels. Drug classes used to treat hyperparathyroidism are parathyroid hormone analogs and modifiers and vitamin D supplements.