Hyperparathyroidism is excessive production of parathyroid hormone (PTH) by the parathyroid glands.
Causes, incidence, and risk factors:
The parathyroid glands are located in the neck, near or attached to the back side of the thyroid gland. They produce parathyroid hormone , which controls calcium, phosphorus, and vitamin D levels within the blood and bone.
When calcium levels are too low, the body responds by increasing production of parathyroid hormone. This increase in parathyroid hormone causes more calcium to be taken from the bone and more calcium to be reabsorbed by the intestines and kidney. When the calcium level returns to normal, parathyroid hormone production slows down.
There are two main types of hyperparathyroidism.
Primary hyperparathyroidism is caused by enlargement of one or more of the parathyroid glands. This leads to too much parathyroid hormone, which raises the level of calcium in the blood. The term "hyperparathyroidism" generally refers to primary hyperparathyroidism.
Secondary hyperparathyroidism is when the body produces extra parathyroid hormone because the calcium levels are too low. This is seen when vitamin D levels are low or when calcium is not absorbed from the intestines. Correcting the calcium level and the underlying problem will bring the parathyroid levels in the normal range.
If the parathyroid glands continue to produce too much parathyroid hormone even though the calcium level is back to normal, the condition is called "tertiary hyperthyroidism." It occurs especially in patients with kidney problems.
Signs and tests:
Blood tests will be done to check for increased levels of parathyroid hormone (PTH), calcium, and alkaline phosphatase, and lower levels of phosphorus . A 24-hour urine collection test can help determine how much calcium is being removed from the body.
Bone x-rays and bone mineral density test can help detect bone loss, fractures, or bone softening.
X-rays, ultrasound, or CT scans of the kidneys or urinary tract may show calcium deposits or a blockage.
Treatment depends upon the severity and cause of the condition. If you have mildly increased calcium levels due to primary hyperparathyroidism and no symptoms, you may just need regular check ups with your doctor.
If symptoms are present or your calcium level is very high, surgery may be needed to remove the parathyroid gland that is overproducing the hormone.
Treatment of secondary hyperparathyroidism depends on the underlying cause.
For specific treatment information see:
The outlook depends on the specific type of hyperparathyroidism.
Complications may include:
Surgery for hyperparathyroidism may lead to low blood calcium levels, which causes tingling and muscle twitching. This requires immediate treatment.
Calling your health care provider:
Call for an appointment with your health care provider if you have symptoms of hyperparathyroidism.
Getting the proper amount of calcium in your diet or through supplements may reduce your risk of secondary hyperparathyroidism.
Wysolmerski JJ. Insogna KL. The Parathyroid Glands, Hypercalcemia, and Hypocalcemia. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008: chap. 266.
Bringhurst FR, Demay MB, Kronenberg HM. Disorders of Mineral Metabolism. In: Kronenberg HM, Schlomo M, Polansky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo: WB Saunders; 2008: chap. 27.