Parathyroid Hyperplasia
DefinitionParathyroid hyperplasia involves enlargement of all four parathyroid glands, which are located in the neck and control calcium metabolism. The condition produces high levels of calcium in the blood (hypercalcemia).
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Overview, Causes, & Risk Factors
Parathyroid hyperplasia causes about 15% of cases of hyperparathyroidism, which leads to elevated levels of calcium in the blood (hypercalcemia).
Parathyroid hyperplasia may occur sporadically (without a family history) or as part of three familial (inherited) syndromes: multiple endocrine neoplasia 1 (MEN 1) and MEN 2A and isolated familial hyperparathyroidism.
In the familial syndromes, a mutated gene is inherited in an autosomal dominant fashion (you only need to get the gene from one parent to develop the condition).
In MEN 1, the problems in the parathyroids are associated with other tumors in the pituitary and the pancreas. In MEN 2A, the overactivity of the parathyroids is caused by tumors in the adrenal gland or thyroid. Adrenal tumors that produce adrenaline (pheochromocytoma) cause the parathyroids to grow; medullary carcinoma of the thyroid, a thyroid cancer, can also cause parathyroid hyperplasia.
The genetic basis of isolated familial parathyroidism is not yet clear.
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