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 tumour A growth within a parathyroid gland. The tumour may cause excess secretion of parathyroid hormone, leading to hyperparathyroidism. Cancers of the parathyroid are very rare; most parathyroid tumours are noncancerous adenomas. An adenoma that causes hyperparathyroidism will be surgically removed (see parathyroidectomy). This usually provides a complete cure. paratyphoid fever An illness identical in most respects to typhoid fever, except that it is caused by SALMONELLA PARATYPHI and is usually less severe. paraumbilical hernia A hernia occurring near the navel. It may occur in obese women who have had several children. parenchyma The functional (as opposed to supporting) tissue of an organ. parenteral A term applied to the administration of drugs or other substances by any route other than via the gastrointestinal tract (for example, by injection into a blood vessel). parenteral nutrition Intravenous feeding (see feeding, artificial).... parathyroid glands
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