Why Women Need to Know More About Their Thyroid

Perhaps you're much more tired than usual. You're chilly even in warm weather. Your skin is dry and globs of moisturizer aren't helping. You're grouchier than normal. All of these problems could be caused by stress or aging. But if you've been feeling bad for more than a couple of weeks, the culprit might be your thyroid, a butterfly-shape gland in the lower front of your neck. Most of the time, you don't know your thyroid is there--and that's as it should be. But when something goes wrong, you're in trouble, because the thyroid is like an air-traffic controller for your body, helping to regulate metabolism, body weight and temperature. Your brain needs thyroid hormone, called thyroxine or T4, to develop and function properly. Your heart can't beat properly without it. And your liver needs thyroid hormone to process cholesterol.

For reasons doctors still don't understand, younger women are much more likely to have thyroid disorders than men. However, as men get older, they are more prone to thyroid problems. The most common problem is hypothyroidism--too little thyroid hormone. It affects about one in 10 people and causes symptoms such as fatigue or feeling cold a lot. Women are particularly vulnerable to hypothyroidism during pregnancy, after delivery and around the time of menopause. The other extreme, hyperthyroidism, or too much thyroid hormone, can also make its first appearance in women around pregnancy. It can cause a racing heartbeat, unexplained weight loss, insomnia and anxiety. And then there's another problem: growths in the thyroid gland called nodules can sometimes be cancerous.

Of these three, hypothyroidism can be the most difficult to detect without a blood test, says Paul Ladenson, director of the Division of Endocrinology and Metabolism at Johns Hopkins. Consider some of the symptoms--fatigue, unexplained weight gain, dry skin, hair loss, slower thinking and depressed mood. All could have many causes, and if your doctor isn't thinking about your thyroid, he or she could easily miss the real explanation. In recent years, doctors have begun to suspect that even mild hypothyroidism may increase a woman's risk for heart disease, which makes diagnosis more important. Recently, Ladenson had a patient who entered the hospital for a non-thyroid-related issue. A routine blood test before surgery showed she had severe hypothyroidism, he says. "And this was a woman who was out on a bikeathon last week," he adds. Now she'll get treatment to help prevent problems from a disease that might have gone undetected and untreated for years because of the lack of obvious symptoms.

Screening consists of a simple, inexpensive blood test of the amount of thyroid-stimulating hormone (TSH) released by your pituitary gland. The test takes advantage of the delicate relationship between the thyroid and the pituitary gland. When your thyroid isn't producing as much thyroxine as your body needs, the pituitary cracks the whip by releasing TSH. (It works the opposite way when the thyroid is cranking out too much--the TSH drops.)

When the TSH level is very high, it's probable that a woman should be treated with synthetic thyroid hormone to replace what her body is missing. But what about mild hypothyroidism? In the past, if your TSH was somewhat high but you still had normal levels of thyroid hormone, doctors might have just monitored the situation with follow-up tests. Some doctors still think that's the best course, but now, with evidence that even a mild problem could lead to increased risk for heart disease, others are arguing for more aggressive intervention. "If hypothyroidism is silently harming women, and some of that harm is not going to be reversible by treating them 10 years from now, when they really get overtly hypothyroid, then you should act," says Ladenson. He helped write American Thyroid Association guidelines that recommend testing the TSH of both men and women after age 35. Since other major medical organizations disagree, your best course is to talk to your doctor if you think your symptoms might be caused by thyroid disease.

In this country, the most common cause of hypothyroidism is a condition called Hashimoto's thyroiditis. It's an autoimmune disease--your immune system is basically turning on you and destroying your thyroid. Autoimmune diseases run in families and are more common in women than men, another reason why thyroid disease may be more of a women's problem. Other examples of autoimmune diseases are rheumatoid arthritis and lupus. If members of your family have any of these conditions, you are more likely to have a thyroid disease, which is another reason to push for a blood test.

Many women also first experience thyroid problems after a pregnancy, a condition called postpartum thyroiditis that occurs in 5 to 10 percent of women. Although the exact cause isn't known, doctors believe that it is an immune disorder very similar to Hashimoto's thyroiditis. "During pregnancy, the immune system is somewhat suppressed so that a woman won't reject this foreign body within her," Ladenson says. "But after delivery, the immune system has a resurgence of vigilance." This can also result in hyperthyroidism. Both are difficult to detect at this time in a woman's life because the symptoms of either one--insomnia, anxiety, fatigue--could also be the result of new motherhood. Sometimes, the thyroid problems disappear within a year of giving birth, but other women go on to have long-term disease.

The causes of thyroid disease may still be a mystery, but the treatment is relatively simple and inexpensive. If you don't have enough thyroid hormone, your doctor will prescribe synthetic thyroxine. It can take several months to get the correct dose because patients usually start at a low dose and work up to a higher one if it's needed. Once you're on thyroid hormone, you have to take it the rest of your life. Ladenson cautions that some things can interfere with the absorption of thyroid hormone, particularly calcium and iron. If you're taking those supplements, make sure that you separate them from the thyroxine by four hours. Soy can also be a problem, so make sure you don't use soy milk in your coffee or cereal with a few hours of taking the pill.

There is no single treatment for people with hyperthyroidism; the therapy depends on your age, the type of hyperthyroidism that you have and your overall health. In some cases, anti-thyroid drugs or radioactive iodone are used to destroy the cells that are making too much hormone. Surgery to remove the thyroid is another option.

Finally, a note about thyroid cancer. It is rare compared to other cancers--it's estimated that there will be about 37,000 new cases this year--but, again, women are more likely than men to be affected. With treatment, the prognosis is excellent; 95 percent of patients survive without a recurrence. Your doctor should feel your thyroid for nodules during a check-up and then can determine whether you need further tests. For more information about thyroid cancer, see the Web site of the Thyroid Cancer Survivors Association.  

For more information about all forms of thyroid disease, check out the patients' resources section of the Web site of the American Thyroid Association.