The parathyroid glands function to regulate calcium levels in the body. Several abnormalities of the parathyroid glands can produce excess parathyroid hormone release, leading to Hypercalcemia. This can be asymptomatic, but also produces a number of symptoms, and can result in serious medical complications. The most common form of hyperparathyroidism is primary hyperparathyroidism. About 85 percent of cases of primary hyperparathyroidism are caused by an abnormal growth of the parathyroid gland; parathyroid adenoma. These are generally solitary, although occasionally two adenomas (double adenoma) occur. The second entity that causes primary hyperparathyroidism is parathyroid hyperplasia. With hyperplasia, all the glands overproduce parathyroid hormone. The hyperplasia may be asymmetric, and clinically appear like an adenoma in some cases. Parathyroid carcinoma is a rare cause of Hypercalcemia mimicking primary hyperparathyroidism. This entity produces very high calcium and parathyroid hormone levels. A small proportion of hyperparathyroidism occurs in a familial fashion. Several types of multiple endocrines Neoplasia produce parathyroid hyperplasia as one of the components of the syndrome. Patients who develop kidney failure may develop secondary hyperparathyroidism. This is generally managed medically, but may occasionally require surgical intervention.
In selected cases of asymptomatic hyperparathyroidism, observation is warranted. This requires close surveillance, monitoring calcium level, urine calcium excretion, and bone density on a periodic basis. In the majority of cases, parathyroidectomy is performed.