It is an extraordinary coincidence that both President and Mrs. Bush have had overactive thyroid glands, a condition called hyperthyroidism that affects about one out of 100 Americans. They have the most common kind of hyperthyroidism, a condition called Graves' disease, named after the Irish doctor who described it more than a century ago.
In this disease, the body's immune system turns against the thyroid gland, inflames it and causes it to produce too much thyroid hormone. These hormones are chemicals that travel in blood throughout the body to regulate our metabolism and the performance of many organs, including the heart.
Graves' disease tends to run in families. It occurs 10 times more often in women than in men. It can occur at any age, but is most common in adults.
Doctors still do not understand what triggers the onset of Graves' disease. One theory is that people get infections that incite the immune system to attack the thyroid, but no specific "bug" has yet been found. Another theory is that stress can cause hyperthyroidism, but this has never been proven, either. Since hyperthyroidism itself causes stress, it is hard to know which is the "horse" and which is the "cart."
The typical symptoms of an overactive thyroid gland can include tiredness, losing weight despite eating well, feeling hotter than other people, trembling hands, fast or irregular heartbeat, unexplained nervousness, trouble falling asleep and weakness.
Someone with hyperthyroidism may notice swelling of the thyroid gland, which is located on the front of the neck beneath the Adam's apple. Individuals with Graves' disease may also develop eye irritation, bulging eyes or double vision.
Sometimes hyperthyroidism may be overlooked because the symptoms are mild and begin slowly. This is especially true in older people, in whom symptoms of hyperthyroidism may be masked. Occasionally, hyperthyroidism can be deceiving. It may appear that a hyperthyroid sufferer has heart disease because of an irregular heart rhythm, or that the victim has cancer because of weight loss. The irregular heart rhythm that President Bush developed, atrial fibrillation, is one which occurs in at least one out of seven older patients with hyperthyroidism.
Doctors can diagnose hyperthyroidism with blood tests that measure the levels of thyroid hormones and another substance called thyroid stimulating hormone (TSH). These tests are very accurate in determining whether a person's symptoms are due to a thyroid condition or not.
Since different kinds of hyperthyroidism may need different treatments, additional tests may be needed to determine the specific cause of thyroid gland over-activity. The thyroid scan, in which a picture of the thyroid gland is taken after a small dose of radioactive material, is often used for this purpose.
Fortunately, hyperthyroidism can be treated, and all of its symptoms and complications can be corrected. There are three kinds of treatment: medications, radioactive iodine and surgery.
Certain symptoms caused by excess thyroid hormone, such as tremor and palpitations, can be improved promptly by medications called beta-blockers. However, these drugs do not control all aspects of hyperthyroidism or really correct the underlying thyroid over-activity.
For Graves' disease, anti-thyroid medications also are often used. These drugs interfere with the thyroid gland's ability to make hormones. When taken faithfully, they are usually effective in controlling hyperthyroidism within a few weeks.
Like any medications, they can have side effects, such as rash, fever or, in a small percentage of cases, a low white blood cell count. However, the main shortcoming of anti-thyroid drugs is that the underlying thyroid gland over-activity often comes back after they are stopped. For this reason, many patients with hyperthyroidism are advised to consider another treatment which permanently corrects hyperthyroidism.
On Thursday, President Bush received a radioactive iodine treatment. Radioactive iodine is concentrated by thyroid cells and gives these cells radiation with very little exposure for the rest of the body. The patient simply comes to the hospital, swallows a radioactive iodine pill and then goes home.
Although the radioactivity is largely gone from the body within a few days, effects on the thyroid take one to three months to develop. Most patients are cured with single dose, and all patients eventually respond to radioactive iodine. The only common side effect of radioactive iodine treatment is underactivity of the thyroid gland, a condition call hypothyroidism.
There is no evidence that radioactive iodine treatment of hyperthyroidism causes cancer of the thyroid gland or other parts of the body, or that it interferes with a woman's chances of becoming pregnant and delivering a healthy baby in the future.