The 4 parathyroid glands are located next to the thyroid gland in the
lower front part of the neck. Athough they are close to the thyroid gland,
the parathyroid glands function independently from the thyroid. The parathyroid
glands make a substance called parathyroid hormone (PTH), which regulates the level of calcium in the blood.
By helping the body absorb calcium from food, PTH maintains a healthful level
of calcium for strong bone function. Also, PTH helps to control the amount
of calcium that is released from bones and then excreted in urine. When the
parathyroid glands make too much PTH, a condition called primary hyperparathyroidism exists, causing abnormally high levels
of calcium in the blood. Hyperparathyroidism can also occur as a result of
other medical problems, such as kidney disease, and is then called secondary hyperparathyroidism. The April 13, 2005, issue of JAMA includes an article about primary hyperparathyroidism.