What Is Hyperparathyroidism?
Primary hyperparathyroidism is a disorder of the parathyroid glands. Most people with this disorder have one or more enlarged, overactive parathyroid glands that secrete too much parathyroid hormone. In secondary hyperparathyroidism, a problem such as kidney failure makes the body resistant to the action of parathyroid hormone. This e-pub focuses on primary hyperparathyroidism.
What Are the Parathyroid Glands? The parathyroid glands are four pea-sized glands located on the thyroid gland in the neck . Occasionally, a person is born with one or more of the parathyroid glands embedded in the thyroid, the thymus, or elsewhere in the chest. In most such cases, however, the glands function normally.
Though their names are similar, the thyroid and parathyroid glands are entirely separate glands, each producing distinct hormones with specific functions. The parathyroid glands secrete parathyroid hormone (PTH), a substance that helps maintain the correct balance of calcium and phosphorous in the body. PTH regulates release of the calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine.
When the amount of calcium in the blood falls too low, the parathyroid glands secrete just enough PTH to restore the balance.
This excess PTH triggers the release of too much calcium into the bloodstream. The bones may lose calcium, and too much calcium may be absorbed from food. The levels of calcium may increase in the urine, causing kidney stones. PTH also acts to lower blood phosphorous levels by increasing excretion of phosphorus in the urine.