Every Day

Jan. - April 2007 Issue

Thyroid Disease Can Cause Fatigue, Weight Gain and More

Diana Maas, MD

Medical College of Wisconsin Endocrinologist

People with diseases of the thyroid gland may suffer from a variety of symptoms, ranging from fatigue and weight gain to anxiety and heart palpitations. Fortunately, many effective treatments are available for thyroid disease. Diana Maas, MD, sheds light on the types of thyroid disease and various treatment options.

Q. What is the thyroid and what does it do?

The thyroid is a gland located in the front of the neck. This gland makes thyroid hormone and controls many functions and organs in the body. The most important of these functions is metabolic rate — how quickly a person metabolizes food and nutrients. The thyroid also affects the body’s temperature and bowel control.

Q. What is thyroid disease?

The most common thyroid problem is an underactive thyroid, or hypothyroidism. The symptoms of an underactive thyroid include fatigue, generalized weakness, problems with memory and mental concentration, weight gain, constipation and feeling cold all the time.

A person can also have an overactive thyroid, or hyperthyroidism. The symptoms of an overactive thyroid are the opposite of an underactive thyroid. They include increased anxiety, tremors, feeling too warm, heart palpitations and racing heartbeat, diarrhea and weight loss.

Thyroid diseases can develop quickly, possibly in just months.

Q. What causes these conditions?

The most common cause of hypothyroidism and hyperthyroidism is autoimmune disease, in which the body produces an antibody that attacks the thyroid. The type of antibody produced determines the form of thyroid disease that you have.

What causes the production of these antibodies? That’s the million dollar question. We don’t really know. We do know the problem tends to run in families and is more common in women. By age 75, about 25 percent of people will have a thyroid disease.

More and more people are being diagnosed with thyroid disease. One reason is that we are screening for it in patients after the age of 60 and in women older than 50. In addition, primary care physicians have become more aware of thyroid problems.

Q. What about thyroid cancer?

As you know, William Rehnquist, former chief justice of the Supreme Court, died recently of thyroid cancer. That is unusual, because most thyroid cancer is treatable and curable. The common form of thyroid cancer is called papillary cancer, and it is curable in the vast majority of cases.

Q. How do you treat thyroid problems?

There are a number of different approaches. If you have underactive thyroid, you could be put on thyroid hormone. This is a synthetic hormone that is extremely safe — safer, in fact, than acetaminophen. The only issue is adjusting the dosage to find the right level. To do this, we look at many things, including the level of thyroid-stimulating hormone (TSH) in the patient’s blood. We also listen to the patient and simply see how he or she is feeling.

If you have thyroid cancer, the treatment is removing the thyroid surgically and then giving the patient a single dose of radioactive iodine. The thyroid uses iodine to make thyroid hormone, so iodine is the “magic bullet” for targeting thyroid cancer.

You can also use radioactive iodine to treat an overactive thyroid — you just use a lower dose. (This treatment may result in an underactive thyroid, in which case you would put the patient on thyroid hormones.)

Another treatment option for an overactive thyroid is anti-thyroid medication. This will normalize the patient’s levels of thyroid hormones, but it is not a permanent treatment. However, this treatment can be advantageous, because symptoms will spontaneously subside for awhile.

A third treatment for overactive thyroid — one that is not often used — is surgical removal. This approach is used for pregnant women with hyperthyroidism that cannot be controlled with a reasonable dosage of anti-thyroid medication. In this case, the safest time to remove the thyroid is the second trimester. Surgical removal is also sometimes used for patients with thyroid eye disease who cannot tolerate anti-thyroid medication.

Q. Isn’t there a controversy surrounding thyroid hormone replacement?

There are two types of thyroid hormone, triiodothyronine (T3) and thyroxine (T4). We recommend using only T4, but some people advocate a combination of T3 and T4. They say the combination is more natural, but actually it is not.

You see, T3 has a very rapid onset of action because it is absorbed very quickly. As a result, giving T3 can be dangerous for the elderly or people with heart disease. It can make a person hyperthyroid for hours, putting a lot of stress on the heart. And the body converts T4 into T3. This takes place in another part of the body besides the thyroid gland, so even if a person is hypothyroid, he or she does not lose the ability to convert this hormone.

Q. What signs of thyroid disease should people be aware of?

The major symptoms of thyroid disease are fatigue and weight gain, along with constipation and cold intolerance. Unfortunately, in our society, tiredness and weight gain can describe many people. If you experience a noticeable change over a couple of years, you should be screened for thyroid problems.

Thyroid screening is a simple blood test to measure a person’s TSH level. All people with a new onset of depression should be screened for underactive thyroid.

Q. When is it time to see a specialist?

Most primary care physicians can treat underactive thyroid. Overactive thyroid can be trickier. In many cases, patients with overactive thyroid should see a specialist, or at least their primary care physician should seek specialist advice. Thyroid cancer should always be treated by an endocrinologist.