Hyperparathyroidism

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Parathyroid glands

Hyperparathyroidism is excessive production of parathyroid hormone by the parathyroid glands.

The parathyroid glands are located at the front and base of the neck around the thyroid gland. They produce parathyroid hormone, which controls calcium, phosphorus, and vitamin D levels within the blood and bone.

When calcium levels are too low, the body responds by increasing production of parathyroid hormone. This increase in parathyroid hormone causes more calcium to be taken from the bone and more calcium to be reabsorbed by the intestines and kidney. When the calcium level returns to normal, parathyroid hormone production slows down.

There are two types of hyperparathyroidism.

Primary hyperparathyroidism is caused by enlargement of one or more of the parathyroid glands. This leads to too much parathyroid hormone, which raises the level of calcium in the blood. The term "hyperparathyroidism" generally refers to primary hyperparathyroidism.

If the parathyroid glands continue to produce too much parathyroid hormone even though the calcium level is back to normal, the condition is called "tertiary hyperthyroidism." It occurs especially in patients with kidney problems.

Related topics:

• Parathyroid related hypercalcemia
• Primary hyperparathyroidism
• Secondary hyperparathyroidism
• Parathyroid adenoma

Review Date: 08/11/2006
Reviewed By: Robert Hurd, MD, Department of Biology, College of Arts and Sciences, Xavier University, Cincinnati, OH. Review provided by VeriMed Healthcare Network.