The parathyroid glands are four small glands in the neck that are part of the endocrine system. They produce parathyroid hormone (PTH), which maintains calcium and phosphorus levels in the blood.
The most common disease associated with the parathyroid glands is overproduction of PTH, known as hyperparathyroidism. Twice as many women as men suffer from this condition and the risk of developing hyperparathyroidism increases with age, as it is more common in patients over the age of 60. Risk factors for hyperparathyroidism include having had radiation treatment to the head or neck. Rarely, cancer may be the cause of the condition.
Causes of Hyperparathyroidism
There are two types of hyperparathyroidism: primary and secondary. Either type may result in the elevation of the level of calcium in the blood, known as hypercalcemia.
Primary hyperparathyroidism originates in the glands themselves, which enlarge and become overactive. The reason for this enlargement is unknown, although in a small percentage of cases there may be a genetic link. Secondary hyperparathyroidism is caused by some other disease process, such as kidney failure or a benign tumor. Other causes of secondary hyperparathyroidism are too much calcium in the diet, vitamin D disorders, and problems absorbing nutrients (malabsorption).
Symptoms of Hyperparathyroidism
While many patients with hyperparathyroidism report only vague symptoms, when too much PTH is secreted into the blood, every organ in the body is effected. Usually, abnormal blood levels are detected early, during routine medical testing, so the condition is not as dangerous as it once was. Nonetheless, the symptoms, if allowed to develop unabated, may be severe. These symptoms include:
- Osteoporosis, a loss of calcium in the bones
- Kidney stones resulting from increased levels of calcium in the urine
- Development of an adenoma, a benign tumor on one of the glands
- Abnormally low phosphorus levels in the blood
- Fatigue, malaise, weakness, depression
- Nausea, vomiting, constipation, loss of appetite
- Increased thirst and urination
- High blood pressure
- Abdominal pain
- Cognitive impairment
- Sleep disturbances
A serious, though rare, complication of hyperparathyroidism is a hypercalcemic crisis, in which a patient may suffer organ failure or coma.
Diagnosis of Hyperparathyroidism
Apart from blood tests for abnormal mineral levels, or elevated levels of PTH, urine tests are administered to detect how much calcium is being excreted in the urine. Bone density scans, ultrasounds, and CT scans of the kidneys or urinary tract may also be performed in order to diagnose hyperparathyroidism.
Treatment of Hyperparathyroidism
Hyperparathyroidism is treated in a number of ways, depending on its cause. Patients are usually advised to remain well-hydrated, to avoid the use of diuretics and to limit dietary phosphorus. In some cases, vitamin D, calcium, and medications to decrease PTH secretion may be prescribed. When hyperparathyroidism is the result of kidney failure, patients may also require dialysis or a kidney transplant.
In most cases, surgery is necessary to successfully treat the condition. Parathyroidectomy, the surgical removal of one or more of the parathyroid glands, has an extremely high rate of success. When only one parathyroid gland is removed, a minimally invasive operation may be performed, either as a radio-guided parathyroid surgery, known as MIRP, or as an endoscopic procedure. Some parathyroid tissue is usually left in place after surgery to help the patient maintain normal PTH and calcium levels.