Hyperparathyroidism

Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). It was first described and treated in the 1930s by Fuller Albright of Massachusetts General Hospital, working at the Mallinckrodt General Clinical Research Center.

Presentation
In cases of primary, tertiary and quintary hyperparathyroidism increased PTH consequently leads to increased serum calcium (hypercalcemia) due to:
 * 1) increased bone resorption, allowing flow of calcium from bone to blood
 * 2) reduced renal clearance of calcium
 * 3) increased intestinal calcium absorption

By contrast, in secondary and quartary hyperparathyroidism effectiveness of PTH is reduced. Alkaline phosphatase levels are elevated in all types of hyperparathyroidism.

In primary hyperparathyroidism, serum phosphorus levels are abnormally low as a result of decreased renal tubular phosphorus reabsorption. This contrasts with secondary hyperparathyroidism, in which serum phosphorus levels are generally elevated because of renal disease.

Etiology

 * Primary hyperparathyroidism results from a dysfunction in the parathyroid glands themselves, with oversecretion of PTH.
 * The most common cause is a benign parathyroid adenoma that loses its sensitivity to circulating calcium levels. Usually, only one of the four parathyroid glands is affected.
 * A less common cause is from multiple endocrine neoplasia (MEN).


 * Secondary hyperparathyroidism is due to resistance to the actions of PTH, usually due to chronic renal failure. The bone disease in secondary parathyroidism along with renal failure is termed renal osteodystrophy.


 * Tertiary, quartary and quintary hyperparathyroidism are rare forms that are caused by long lasting disorders of the calcium feedback control system.

Signs and symptoms
Almost all patients with hyperparathyroidism have symptoms. Most will have 3 or 4 of the 14 symptoms associated with parathyroid disease and high calcium levels. Since calcium is responsible for the electical conduction within our nervous system, high blood calcium levels have a direct effect on the nervous system. Thus, most of the symptoms of parathyroid disease are "neurologic" in origin. The most common symptom is fatigue and tiredness. Other very common symptoms are lack of energy, memory problems, depression, problems with concentration, and problems sleeping. Other manifestations of hyperparathyroidism usually involve the kidney (stones) and the skeletal system (bone pain due to the development of osteoporosis).

The symptoms of hyperparathyroidism can be classically remembered by the rhyme "moans" (complain that you don't feel good), "groans" (abdominal pain, GERD), "stones" (kidney), "bones" (bone pain), and "psychiatric overtones" (lethargy, fatigue, depression, memory problems).

Almost all patients with hyperparathyroidism will develop osteoporosis. If untreated, this osteoporosis can be extreme. Unfortunately, medicines are usually not useful for treating the osteoporosis associated with hyperparathyroidism until the parathyroid tumor is removed. Osteoporosis associated with hyperparathyroidism is caused by the high parathyroid hormone that is secreted by the overactive parathyroid gland(s). This excess parathyroid hormone (PTH) acts directly on the bones to remove calcium from the bones. Thus, the high calcium in the blood comes from the bones. Removing the offending parathyroid gland will usually cause a significant improvement in the osteoporosis, often reversing this process back to normal bone density over several years.

Other symptoms include: headaches, gastroesophageal reflux, decreased sex drive, thinning hair, hypertension, and heart palpitations which are often due to bouts of atrial fibrilation.

Almost all patients will have symptoms if their calcium is high and the right questions are asked. Removing the parathyroid tumor which is causing the excess parathyroid hormone will eliminate the symptoms in most patients within several days or weeks. Often it is life-changing when the parathyroid tumor is removed.

Diagnosis
The gold standard of diagnosis is the PTH immunoassay. Once an elevated PTH has been confirmed, goal of diagnosis is to determine whether the hyperparathyroidism is primary or secondary in origin by obtaining a serum calcium level:

Treatment
Treatment is first and foremost directed at hypercalcemia, if symptomatic patients are sent for surgery to remove the parathyroid tumor (parathyroid adenoma). (see hypercalcemia) Most experts now believe that almost all patients with hyperparathyroidism should be evaluated for surgery. Watching and waiting has been falling out of vogue since it is being realized that the disease will rarely stay the same. It will almost always progress as the tumor grows.


 * (see primary hyperparathyroidism)
 * (see secondary hyperparathyroidism)