Parathyroid Hyperparathyroidism

Hyperparathyroidism results from the overactivity of one or more of the parathyroid glands which generate increased amounts of parathyroid hormone (PTH). There are several types of hyperparathyroidism, influencing the diagnostic evaluation and the recommended surgical treatment.

Sporadic primary hyperparathyroidism

Each year, 100,000 new cases of sporadic primary hyperparathyroidism are diagnosed in the United States, affecting 0.2% to 0.5% of the population. Women are more commonly affected than men and the incidence of the disease increases with age. Most cases (85%) are the result of a single parathyroid gland malfunction caused by the development of a benign tumor, known as an adenoma.

Parathyroid hyperplasia

In approximately 15% of hyperparathyroid cases, two or more glands grow into adenomas (tumors) resulting in a condition called parathyroid hyperplasia. This disorder is often marked by an increased level of calcium in the blood (hypercalcemia) following an operation for what was thought to be a single adenoma. Hyperplasia can occur sporadically or by a genetic abnormality in Multiple Endocrine Neoplasia (MEN) 1 and 2. MEN-1 influences the development of tumors in the pituitary gland and pancreas, whereas MEN-2 influences the thyroid and adrenal glands.

Parathyroid cancer

See separate section on parathyroid cancer.

Secondary Hyperparathyroidism

This form of hyperparathyroidism typically occurs in patients who have kidney failure or kidney disease. A form of parathyroid hyperplasia, it stems from/on blood-calcium levels.

Tertiary Hyperparathyroidism

Caused by known kidney failure or disease, this disorder is characterized by high calcium levels when hyperplastic parathyroid glands begin to function autonomously.

Symptoms

Depending on the type, hyperparathyroidism may cause virtually no symptoms or it may create severe, life-threatening symptoms particularly when associated with very high calcium levels. Patients may experience one or more of the following symptoms:

Complications can also arise in the form of associated conditions such as:

Diagnosis

Because many patients are entirely asymptomatic, diagnosis often occurs after the detection of mildly elevated calcium levels during routine blood work. In order to diagnose associated conditions/complications, however, bone densitometry (bone mineral density) tests, as well as monitoring urinary excretion of calcium and creatinine and kidney X-ray are used.

Treatment

Treatment options for hyperparathyroidism include surgery and medical therapy. Surgery to remove the affected gland(s) most often cures this disorder. When performed by an experienced surgeon, the operation is successful in over 95% of cases and serious surgical complications are uncommon. Surgery is recommended for patients who have overt symptoms or complications and for asymptomatic patients who meet the following criteria:

• Young age (50 years or less)
• Significant decrease in bone mineral density
• At least 30% decrease in kidney function
• The presence of significant calcium levels in the urine
• A calcium level 1.0 mg/dl above the upper limit of normal

Medical therapy may be appropriate for patients with mild hypercalcemia (excess of calcium) with no associated symptoms or complications. Possible medical treatments include estrogen-receptor modulators for postmenopausal women and bisphosphates to prevent bone loss. If surgery is not performed, careful monitoring of blood calcium levels, kidney function, and bone densitometry must be enforced in order to prevent the progression or the disorder.