Two pairs of oval, pea-sized glands that lie behind the thyroid gland in the neck. Some people have only 1 parathyroid gland or have extra glands in the neck or chest. The glands produce parathyroid hormone, which helps regulate the level of calcium in the blood; even small variations in calcium level can impair muscle and nerve function. Rarely, the parathyroid glands may become overactive (in a condition called hyperparathyroidism) or underactive (see hypoparathyroidism).
Parathyroid glands |
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