Hyperthyroidism

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VOL 106 / NO 4 / OCTOBER 1, 1999 / POSTGRADUATE MEDICINE

When your thyroid gland is overactive, it produces too much thyroid hormone for your body. This is called hyperthyroidism, and it can cause a number of problems.

The most common cause of hyperthyroidism is a disorder called Graves' disease. It runs in families and occurs more often in women than in men. The precise cause of Graves' disease is unknown. Hyperthyroidism can also be caused by thyroiditis, an inflammation of the thyroid gland that often disappears in a few weeks and may be caused by an infection. Toxic nodular goiter also can occur when part of the thyroid gland enlarges and produces too much thyroid hormone. In some cases, too much iodine in your diet or taking too many thyroid pills for low thyroid function (hypothyroidism) can cause high hormone levels. Many patients with hyperthyroidism are in their 20s or 30s, but it occurs in the elderly as well.

What are the symptoms?

In some patients, symptoms clearly indicate hyperthyroidism. In others, symptoms are not so obvious. Problems can occur in many parts of the body. Most of the time, you will notice some of the following if you have hyperthyroidism:

• Your eyes may protrude or seem to be large and staring (because of swelling behind the eyes and injury to the muscles used to blink).
• Your heart may pound or beat very fast.
• You may have an enlarged thyroid gland (sometimes called a goiter), which causes a swelling in the front part of your neck.
• You may feel nervous, anxious, irritable, or forgetful. You might fidget or tremble. Elderly people may feel listless or depressed.
• Without changing your eating habits, you may be losing weight.
• You may be too warm when people around you are comfortable. You may sweat more than usual or have dry, itchy skin.
• You may have trouble sleeping.
• Your hair may fall out when you wash and comb it.
• You may have diarrhea or frequent bowel movements.

What should you do if you have these symptoms?
Tell your doctor about them. The level of thyroid hormone in your body can be measured from a blood sample, and other tests are helpful as well. Your doctor may decide to test your thyroid gland for radioactive iodine uptake, or a thyroid scan can be done to see how the thyroid gland is working.

How is hyperthyroidism treated?
One method is to destroy part of the overactive thyroid gland with radioactive iodine therapy. This is the most common treatment used in the United States for hyperthyroidism. However, thyroid hormone pills are needed after treatment to supply your body with the correct amount of hormone to function properly. Radioactive iodine treatment is not used during pregnancy or breast-feeding, and women are discouraged from becoming pregnant for about 6 months after radioactive iodine therapy.

Another treatment is to take an antithyroid drug that keeps the excess hormone in check. The problem with this treatment is that it has a short period of effectiveness and can cause some problems, such as skin rashes, joint pain, fever, or allergic reactions.

Thyroid surgery, which was common in the past, is seldom used today. However, surgical removal of the thyroid gland might be appropriate in some patients if the other treatments aren't possible. What is best for you depends on many things, such as your age, other health concerns, and whether you are or soon want to be pregnant.

All of these treatments are very successful, but you will need some follow-up visits to get drug dosages just right.

How the thyroid gland works
Hormone released by the hypothalamus in the brain signals your pituitary gland to make a special hormone called thyrotropin, or thyroid-stimulating hormone (TSH). This hormone then triggers your thyroid gland to produce thyroxine (T4) and triiodothyronine (T3), which help regulate your metabolism. If your thyroid sends out too much of these hormones, your heart speeds up, you often feel warm and sweaty, and you may lose weight and have trouble sleeping. Some people notice a change in their eyes, which seem to protrude or appear to be unusually large.

This information is not a substitute for medical treatment.

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