The parathyroid glands are located immediately behind the thyroid gland. Most people have four parathyroid glands (about 5% of the population has a fifth gland). These glands regulate the level of calcium in the blood by producing a hormone called PTH (parathyroid hormone) which stimulates the release of calcium from bones and the absorption of calcium by the kidney. The most common indication for surgery of the parathyroid glands is primary hyperparathyroidism. In this condition, the glands secrete too much PTH and the blood levels of calcium become too high and place the patient at risk for developing kidney stones, bone fractures, pancreatitis, hypertension and gout. Other symptoms include muscle pain and weakness, constipation, depression, anxiety, loss of appetite, increased thirst and urination, weight loss, lethargy, and rarely, a palpable neck mass.
The most common causes of primary hyperparathyroidism are adenoma, hyperplasia, and cancer. Adenomas are benign tumors that develop in one or more of the glands and account for about 85% of the cases of primary hyperparathyroidism. 10% to 15% of the cases are caused by hyperplasia (abnormal growth of all of the glands) while cancer accounts for less than 1% of the cases. About 1 in 4,000 people in the United States develop primary hyperparathyroidism with the main risk factors being family history of hyperparathyroidism and radiation to the neck. The incidence of the disease increases with age and is most common among postmenopausal women. Some individuals develop hyperplasia of the parathyroid glands as part of a systemic problem with their endocrine system called ãmultiple endocrine neoplasiaä syndrome. In this syndrome, patients develop tumors of one or several other endocrine glands including thyroid and adrenal glands.
The treatment of choice for primary hyperparathyroidism is surgery. Adenomas are removed and all abnormally enlarged parathyroid glands are biopsied. Hyperplasia usually affects all four parathyroid glands and requires their removal. Some parathyroid tissue is retained and reimplanted surgically where it will continue to produce PTH and regulate blood calcium levels. Carcinoma of the parathyroid glands requires removal of the affected gland and involved adjacent soft tissue and regional lymph nodes.
The possible postoperative complications of parathyroid surgery include injury to the laryngeal nerves with resulting hoarseness. Injury to the parathyroid glands can also result in low blood calcium requiring life-long calcium replacement.