Definition

A condition in which the parathyroid glands (four pea-sized glands found in the neck) are larger than normal. This condition may cause the glands to make too much parathyroid hormone, which can lead to a loss of calcium from the bones, too much calcium in the blood, broken bones, and other health problems. Parathyroid hyperplasia may be caused by chronic kidney disease, low vitamin D levels, and other medical conditions. It may also occur in people who have certain inherited disorders, including multiple endocrine neoplasia (MEN) syndrome and familial isolated hyperparathyroidism.