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Parathyroid Illness

The parathyroid glands are small, mustard-colored endocrine glands about the size of a grain of rice. Four in number, they are normally found on the posterior surface of the thyroid gland as shown in the illustration. Although the exist in anatomic proximity to the thyroid, their function is unrelated to that of the larger gland.

The parathyroids produce "parathyroid hormone" (also called "parathormone"). It is the function of this hormone to very tightly regulate the level of calcium in the blood. In fact, calcium is the only element within the body that has such a regulatory system of its own. The importance of calcium levels and their stability is illustrated by the following facts.

Calcium is needed o provide the electrical energy for the nervous system. The most important thing that calcium does in the human body is provide the means for electrical impulses to travel along nerves. Calcium is what the nervous system uses to conduct electricity. Hence, the most common symptoms of parathyroid disease and high calcium levels are related to the nervous system (depression, weakness, tiredness, etc).

As with nerves, muscles use changes in calcium levels inside the cells to provide the energy for contraction. When the calcium levels are not correct, one can feel weak and have muscle cramps.

Calcium is also used to make our bones strong, but this is secondary. The bones serve as the calcium storage system from which the parathyroids direct regular "deposits" and "withdrawals." The continual process of putting calcium into the bones and taking calcium out has the sole purpose of keeping calcium levels in the blood at the correct level. This ensures proper neuromuscular function.

The parathyroid glands have a rich blood supply, and this allows them to closely measure the calcium level in the blood. If the glands find the calcium level to be low, they release more parathormone. This circulates to the bones, directing them to breakdown more calcium for the circulation, and to the intestine, instructing them to absorb more calcium from the diet.

Hyperparathyroidism

The main disease of the parathyroids is a condition of overactivity known as "hyperparathyroidism".This condition is almost always the result of a benign tumor (called a "parathyroid adenoma") developing within one of the four glands. Such a tumor looses it normal inhibition controls and continues to create and release parathormone even when blood calcium levels are high.In response to the high levels of calcium in the blood caused by the over-secreting tumor, the other three glands shrink and become dormant.

Although a single, benign tumor is the cause in about 97% of cases of primary hyperparathyroidism, in a few percent of cases, generalized enlargement of all four glands may be found (so-called "parathyroid hyperplasia"). Even more unusual (0.5%) is the presence of two adenomatous glands and two normal ones.

Symptoms

The symptoms of hyperparathyroidism are many and can at times be subtle. They also do not tend to correlate with the blood calcium level, meaning that someone with a slight elevation may be more symptomatic than another with a higher elevation.

  • Loss of energy
  • General malaise
  • Depression
  • Loss of concentration and/or memory
  • osteoporosis / osteopenia
  • bone pain
  • disturbed sleep patterns
  • irritability
  • kidney stones
  • headaches
  • high blood pressure
  • heart palpitation

Diagnosis

The doctor will want to measure the level of both the calcium in the blood and the level of parathyroid hormone. An elevated calcium together with an elevated parathormone indicate hyperparathyroidism. If the values are borderline, the doctor may do a 24 hour urine test to measure the calcium in the urine. Similarly, if the results are vague, checking the "ionized" calcium in the blood (that calcium that is unbound to serum proteins) may also help confirm the diagnosis.

Treatment

The only treatment for primary hyperparathyroidism is the surgical removal of the involved gland(s).In earlier days this would require the surgeon to make a large incision in the neck through which he would explore the areas behind both sides of the thyroid. Several hours of surgery under general anesthesia was required if the doctor was to find the gland(s) at fault and remove them.

Identifying the location of the offending gland before an operation is begun can be of enormous help and may allow the surgeon to perform a much more limited operation.

The best way to detect the location of the secreting tumor is with a "sestamibi scan." In this procedure, a small protein labeled with radioactive technetium-99 is injected intravenously. The radionuclide will become concentrated in the offending gland and will "light up" when the scanner takes an image.

This test is able to find an involved gland in about 90% of cases.Also, when it does so, it proves correct in its identification about 99% of the time. What this means is that the scan will find the majority of tumors, but can miss some. However, when it does find something, it has nearly always made the correct identification.

While CT scan, ultrasound and MRI may have occasional use in the workup of hyperparathyroidism, Sestamibi scan is the most sensitive and specific tool. However, the scan may produce poor results when thyroid nodules are present or in the setting of multigland disease.

Standard Parathyroid Surgery

In standard (old style) surgery for hyperparathyroidism, the surgeon makes a lengthy incision across the neck to gain access to both sides. After separating the muscles, he will expose the thyroid gland and dissect around it to its back where most parathyroids are found. If one gland is obviously larger than the other three, it will be presumed the culprit and will be removed. In the uncommon circumstance of finding four similarly enlarged glands, the surgeon will remove three or perhaps three and part of the fourth to treat the overactivity. This surgery can take 2 or more hours and will usually produce cure in 85-90% of cases.

Minimally Invasive Parathyroid Surgery

Some years ago, Dr. Caruana brought an improved technique to his patients that employs a "minimally invasive" approach to the treatment of hyperparathyroidism. If pre-op evaluations reveal that the disease is limited to one gland, a procedure may be done under local anesthesia using a tiny incision for the introduction of an endoscope. Using this equipment, Dr. Caruana can remove the offending gland in a very short operation that requires no hospital stay. Adding to the success rate of the surgery is the use of "intra-operative PTH monitoring." By measuring the levels of parathyroid hormone during the operation and documenting their substantial decline after gland removal, Dr. Caruana can deliver extremely high cure rates.