The primary disease of parathyroid glands is overactivity—too much parathyroid hormone is produced. This is called hyperparathyroidism. Under this condition of hyperparathyroidism, one or more of the parathyroid glands behaves inappropriately by making excess hormone regardless of the level of calcium. In other words, the parathyroid glands continue to make large amounts of parathyroid hormone, even when the calcium level is normal and they should not be making hormone at all. Over-production of parathyroid hormone by overactive parathyroid glands (hyperparathyroidism) can rob you of your health, making you feel run down and tired, causing osteoporosis, and many other serious problems. Fortunately, hyperparathyroidism can be fixed with new minimally invasive surgery techniques in most people in under 20 minutes.
What Causes Excess Hormone Production?
The most common cause of excess hormone production is the development of a benign (non-cancerous) tumor in one of the parathyroid glands. This enlargement of one parathyroid gland is called a parathyroid adenoma, and it accounts for 96% of all patients with primary hyperparathyroidism.
The most common situation is that one of the parathyroid glands has developed a tumor that is secreting all the hormone. The other 3 glands are small and are responding appropriately to the high calcium by becoming dormant.
This out of control parathyroid gland is rarely ever cancerous (less than one in 2,500); however, it slowly causes damage to the body because it induces an abnormally high level of calcium in the blood, which can slowly destroy a number of tissues. Parathyroid adenomas typically are much bigger than the normal pea-sized parathyroid and will frequently be about the size of a walnut.
Approximately 3% or 4% of all patients with primary hyperparathyroidism will have an enlargement of all 4 parathyroid glands, a term called parathyroid hyperplasia. In this instance, all of the parathyroid glands become enlarged and produce too much parathyroid hormone. This is a much less common scenario, but the end results on the tissues of the body are identical.
An even rarer situation occurs in less than 1% of the people who have 2 parathyroid adenomas while having 2 normal glands. This is very uncommon and can make the diagnosis and treatment of this disease a bit tricky.
How Many Parathyroids Are Affected?
A scientific study of 6,331 patients with primary hyperparathyroidism examined how many glands typically go bad in this disease. This study included data collected on a portion of patients with this disease over 10 years (1987-1997). The complete data and statistical analysis was published in March 1998 by Dr. James Norman's group in the Journal of the American College of Surgeons.
The results are as follows:
Some experts believe the incidence of multi-gland disease (hyperplasia and multiple adenomas) is slightly over reported. This data is obtained from patients who have undergone a full neck exploration and had all of the glands biopsied. Therefore, the data is based on a microscopic examination and not on whether any hormone is produced. It is unknown if these other glands would be clinically active (produce hormone).
The only way to know is to remove only one gland while leaving the others untouched and then following these patients for a number of years. The bottom line is that somewhere between 94% and 96% of all patients with hyperparathyroidism have one bad gland and 3 normal glands.
Symptoms of Hyperparathyroidism
Since hyperparathyroidism was first described in 1925, the symptoms have become known as "moans, groans, stones, and bones." Although most people with primary hyperparathyroidism claim to feel well when the diagnosis is made, the majority will actually say they feel better after the problem has been cured.
This can only be known retrospectively when patients are allowed to comment on how they feel several months after the operation.
Many patients who thought they were asymptomatic pre-operatively will claim to sleep better at night, be less irritable, and find that they remember things much easier than they could when their calcium levels were high.
In some studies, as many as 92% of patients claimed to feel better after removal of a diseased parathyroid gland, even when only 75% claim they felt "bad" before the operation. Patients with persistently elevated calcium levels due to overproduction of parathyroid hormone also can have complaints of bone pain.
In the severe form, bones can give up so much of their calcium that the bones become brittle and break (osteoporosis and osteopenia). This problem is even more of a concern in older patients. Bones can also have small hemorrhages within their center that will cause bone pain.
Other symptoms of hyperparathyroidism are the development of gastric ulcers and pancreatitis. High levels of calcium in the blood can be dangerous to a number of cells, including the lining of the stomach and the pancreas, causing both of these organs to become inflamed and painful (ulcers and acute pancreatitis).
Another common presentation for persistently elevated calcium levels is the development of kidney stones. Since the major function of the kidney is to filter and clean the blood, they will be constantly exposed to high levels of calcium in patients with hyperparathyroidism. The constant filtering of large amounts of calcium will cause the collection of calcium within the renal tubules, which leads to kidney stones.
In extreme cases, the entire kidney can become calcified and even take on the characteristics of bone because of deposition of so much calcium within the tissues. Not only is this painful because of the presence of kidney stones, but in severe cases, it can cause kidney failure.
The incidence of these problems depends primarily on the duration of the disease and its severity. Everybody will lose bone density, which is progressive. Pancreatitis and ulcers are much more rare. Even though the majority of patients claim they feel "just fine" when this disease is diagnosed, almost 80% of them claim to feel better (sleep better, etc) 3 months after the problem has been fixed. Do not elect to undergo surgery (or decide not to do so) based upon how you feel. Remember, the typical patient has had this disease for several years before it was ever found because its symptoms are so silent. The good news is that it can be cured with a routine operation that carries a success rate of about 95% and a complication rate of around 1% or less. Some centers are even performing minimally invasive surgery for this disease, which can be accomplished under local anesthesia.