Parathyroid Tumors

Parathyroid adenomas are benign tumors that secrete excessive amounts of parathyroid hormone (PTH), leading to hyperparathyroidism Hyperparathyroidism Hyperparathyroidism occurs when one or more of the parathyroid glands become overactive, causing elevated serum levels of parathyroid hormone and leading to hypercalcemia. Patients may be asymptomatic... read more which causes hypercalcemia Hypercalcemia Hypercalcemia is a total serum calcium concentration > 10.4 mg/dL (> 2.60 mmol/L) or ionized serum calcium > 5.2 mg/dL (> 1.30 mmol/L). Principal causes include hyperparathyroidism... read more , hypophosphatemia Hypophosphatemia Hypophosphatemia is a serum phosphate concentration < 2.5 mg/dL (0.81 mmol/L). Causes include alcohol use disorder, burns, starvation, and diuretic use. Clinical features include muscle weakness... read more , and excessive bone resorption (leading to osteoporosis Osteoporosis Osteoporosis is a progressive metabolic bone disease that decreases bone mineral density (bone mass per unit volume), with deterioration of bone structure. Skeletal weakness leads to fractures... read more ).

Parathyroid adenomas are most often isolated solitary adenomas and are more common among older women. However, parathyroid adenoma may occur as hereditary syndromes in patients with multiple endocrine neoplasia Overview of Multiple Endocrine Neoplasias (MEN) The multiple endocrine neoplasia (MEN) syndromes comprise 3 genetically distinct familial diseases involving adenomatous hyperplasia and malignant tumors in several endocrine glands. MEN 1 involves... read more .

Most parathyroid adenomas do not cause symptoms and are identified when blood tests done for another reason reveal elevated calcium levels. Symptoms of hyperparathyroidism may occur and are usually due to hypercalcemia or kidney stones Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more .

Diagnosis of hyperparathyroidism is based on the presence of an elevated PTH level in patients with hypercalcemia. In patients with elevated levels of PTH, further studies are needed, including measurement of calcium and phosphorus levels and imaging to evaluate bone density and determine the presence of kidney stones.

Treatment is usually surgical removal of the affected parathyroid gland. Parathyroid surgery should done by a surgeon experienced in operating on the parathyroid glands.

Localization of parathyroid tissue before surgery on the parathyroid(s) is sometimes done, especially when minimally invasive surgery is planned. Several techniques have been used, and all are highly accurate:

Technetium-99 sestamibi, a radionuclide agent for parathyroid imaging, is more sensitive and specific than older agents and may be useful for identifying solitary adenomas.

Occasionally, the calcimimetic, cinacalcet, is given to decrease secretion of PTH.

Parathyroid cancer is rare.

Risk factors for parathyroid cancer include

Parathyroid carcinomas are usually slow growing. If the initial surgery is able to remove the entire gland without rupture of the capsule, long-term survival without recurrence is common. Recurrent cancer is usually slow growing and spreads locally in the neck. Occasionally, parathyroid cancers are more aggressive with distant metastases.

Parathyroid carcinomas cause hyperparathyroidism similar to adenomas except that the hyperparathyroidism and hypercalcemia due to parathyroid carcinoma is more severe. Calcium levels of 14 to15 mg/dL (3.5 to 3.7 mmol/L) should raise concern for carcinoma.

Symptoms are due to hypercalcemia Hypercalcemia Hypercalcemia is a total serum calcium concentration > 10.4 mg/dL (> 2.60 mmol/L) or ionized serum calcium > 5.2 mg/dL (> 1.30 mmol/L). Principal causes include hyperparathyroidism... read more .

Diagnosis includes blood tests to detect elevated levels of PTH and imaging tests to locate tumors.

Parathyroid cancers are usually removed surgically. Sometimes radiation therapy and/or chemotherapy are also needed.

Discovery of a number of mutations in established cancer genes in parathyroid carcinoma cells raises hope of new treatments using targeted therapeutic agents developed for other types of cancers. Unsuspected germline mutations have also been discovered in a minority of patients with parathyroid cancer.

Genetic screening of family members in select cases has been recommended.