Hyperparathyroidism
What is hyperparathyroidism?
Hyperparathyroidism is a condition that occurs when there is too much secretion of parathyroid hormone. This causes the calcium level in the blood to be inappropriately high. Hyperparathyroidism occurs in three forms: primary, secondary and tertiary.
Primary hyperparathyroidism occurs when the regulation of parathyroid hormone secretion by the feedback from the serum calcium is disturbed and the oversecretion of parathyroid hormone is not inhibited by the elevated calcium. Primary hyperparathyroidism is quite common and occurs in almost 0.1 percent of the population. It is seen most frequently in older women. It is the most common cause of hypercalcemia in non-hospitalized patients.
Secondary hyperparathyroidism most commonly occurs in patients with chronic renal disease where the absorption of calcium from the intestine is impaired so that the parathyroid glands have to compensate and secrete more parathyroid hormone.
Tertiary hyperparathyroidism occurs when the renal disease is corrected but the parathyroid hormone over secretion continues autonomously. The excess parathyroid hormone secretion acts to take calcium from the bony skeleton to increase the level in the blood. This causes generalized weakening of the bones from osteoporosis and osteopenia. The high calcium in the blood has to be excreted in the urine so kidney stones can often occur.
What are symptoms of hyperparathyroidism?
The classic symptoms of hyperparathyroidism include renal stones, painful bones, abdominal groans, psychic moans, fatigue, tiredness, and hypertension. Many patients with hyperparathyroidism are thought to be asymptomatic but when questioned closely they will have:
Hyperparathyroidism can occur as an inherited problem and can be caused by prior exposure to radiation. In most patients, it is unknown why they develop this problem. Enlarged parathyroid glands are almost never able to be felt when examining the neck. If a lump is felt, it is most often a thyroid nodule. Thyroid problems can occur frequently in patients with hyperparathyroidism and vice versa. So patients with hyperparathyroidism should be checked for thyroid disease and patients with thyroid disease should be checked for hyperparathyroidism.
The symptoms of a parathyroid tumor may resemble other conditions or medical problems. Always consult your physician for a diagnosis.
How is hyperparathyroidism diagnosed?
Hyperparathyroidism is diagnosed by blood tests. Measurement of serum calcium and parathyroid hormone are the means for this. The serum calcium level is almost always elevated and the parathyroid hormone level is inappropriately high for the level of calcium. There are other causes of elevated calcium but these are usually able to be identified when a doctor takes a complete history and physical examination.
Surgery is indicated for all patients with symptomatic hyperparathyroidism unless their medical condition makes the risk of operation too high. Kidney stones, loss of bone density (osteoporosis), and muscle weakness have the best response to parathyroidectomy but even problems with depression, mood, weakness, and loss of energy and stamina can be improved in many patients. Research has shown this type of benefit in patients who have their hyperparathyroidism corrected with surgery.
After the diagnosis of hyperparathyroidism is confirmed, an attempt is made to identify and localize an enlarged parathyroid gland. The tests that are most useful for this are ultrasound of the neck, which can be done in the office, and nuclear medicine scan using technetium sestamibi.
Treatment for a parathyroid tumor:
Surgery to remove the tumor or enlarged glands is currently the only effective treatment for hyperparathyroidism.
If an enlarged parathyroid gland has been found on the sestamibi scan, ultrasound or both, a minimally invasive parathyroidectomy can be performed. Minimally invasive parathyroidectomy involves a small (approximately an inch long) incision in the neck over the enlarged parathyroid gland. This can be done under local or general anesthesia depending on patient preference. A skilled surgeon can find the enlarged gland and remove it quite safely. In order to be sure that the gland is the only cause of the hyperparathyroidism, it is possible to measure parathyroid hormone levels during the operation. The levels should return to normal if all abnormal parathyroid tissue has been removed. If they do not, the surgeon will have to look for the remaining glands until the levels correct. This occurs only in a small minority of patients.
In experienced hands, parathyroidectomy is a very safe operation. There is really no risk of infection or need for blood transfusion. There is a 1 in 100 to 1 in 1000 chance of being hoarse after the operation and an equally small risk that the patient will have to take medicine to control their calcium metabolism since some patients can develop very low blood calcium. This is usually because their bones now will try to replace all the calcium that has been lost over time.
Rarely can an abnormal parathyroid gland be located in the chest. This can be removed with thoracoscopy in many patients so a large incision is again avoided. Thoracoscopy is done by making small incisions between the ribs so that a scope with a camera and instruments to dissect and remove the parathyroid glands can be put into the chest. This method is much less painful and allows the patient to return to their normal activity much quicker.
Secondary hyperparathyroidism requires removal of all of the parathyroid glands since they are all overactive. The parathyroid glands can be transplanted to the muscle in the forearm so that normal parathyroid function can be maintained. Parathyroid tissue can also be frozen and re-transplanted when it is thawed at a later date if the patient needs more parathyroid tissue.
Click here to view the
Online Resources page of this Web.
|
Endocrinology
Endocrinology
Endocrinology & Metabolism
Parathyroid Glands: Location and Function