En español | You may have never given your thyroid a moment's thought until something like a racing heart, fatigue or mysterious weight gain sent you scuttling to your doctor's office in search of a fix. Could this much-discussed but little-understood gland at the front of your neck be to blame?
Yes. In fact, your tiny thyroid gland (which normally weighs less than an ounce) plays a significant role in everything from your heart rate to your toenails. It's been called your body's control center because the hormones it produces keep your brain, heart rate, breathing, nervous system, weight, body temperature, cholesterol, metabolism and more operating at top efficiency.
How it works: The thyroid is signaled by the pituitary and the brain's hypothalamus to turn iodine from the food you eat into the hormones triiodothyronine (T3) and thyroxine (T4), which are then sent through your bloodstream to feed your body's cells. In a feedback loop, the pituitary monitors the hormone levels in your blood and signals the thyroid to either produce more or less of them.
What can go wrong?
For more than 5 percent of adults — and far more women than men — the T3 and T4 balance gets out of whack. Experts say that about 1 in 8 women will experience a thyroid problem in her lifetime.
Continued overproduction of these hormones by the thyroid, or hyperthyroidism (including Graves’ disease), is most common in women of reproductive age and can cause the following:
- rapid heart rate
- irritability or moodiness
- nervousness or hyperactivity
- sweating or sensitivity to high temperatures
- trembling or tremors
- hair loss
- unexpected weight loss
- difficulty sleeping
- muscle weakness
- increased thirst
If your thyroid is not able to produce enough T3 and T4, or is underactive, you have hypothyroidism. You may also suffer from an autoimmune disease called Hashimoto, which is the most common cause of hypothyroidism. Peter Singer, M.D., professor of clinical medicine at the Keck School of Medicine, University of Southern California, notes that 80 percent of such cases are in women. And rates increase with age: 3 percent of women in their 40s, about 10 percent of women 65 years old and 20 to 25 percent of women 75 or older have this problem.
The symptoms of hypothyroidism can be any of the following:
- trouble sleeping
- fatigue and lack of energy
- inappropriate weight gain or inability to lose weight
- difficulty concentrating, brain fog or memory loss
- dry skin and hair, and brittle nails
- hair loss
- sensitivity to cold temperatures
- joint and muscle aches
- decreased libido
Rarer problems of the thyroid include abnormal growth of the gland, such as goiters, which can compress the windpipe; nodules (50 percent of people will develop them as they age; they are benign in most cases); and thyroiditis, which results from inflammation within the gland. Cancer in the thyroid can develop, too, and is both treatable and survivable, especially if caught early.
Testing your hormone levels
To determine if you have an issue with your thyroid, a doctor will order a simple blood test measuring TSH, which should fall between .4 and 4.0 milli-international units per liter (mIU/L).
James Hennessey, M.D., director of clinical endocrinology at Beth Israel Deaconess Medical Center, notes that studies indicate that higher levels of TSH can be normal as we age.
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To get the most accurate results from the blood test, experts recommend that you give your doctor a complete list of all medications you take, including vitamins and supplements, which can influence both test results and thyroid function. Supplements that claim to “naturally boost metabolism” can be especially problematic, as they often contain bovine thyroid tissue, which may contain hormones that disrupt your own thyroid function.
Eating large amounts of soybean products, walnuts, cottonseed meal, kelp or seaweed — as well as taking supplements with iodine, calcium or iron — can also cause problems with thyroid function and blood test accuracy. Consuming excessive amounts of sushi or tofu can skew test results, too. And, Singer says, if you take or use biotin products (in supplements or in items like shampoo), these should be discontinued several days before testing. For the most precise results, experts also advise that you have your blood drawn in the morning before eating or drinking anything.
Treating the problem
Hypothyroid medications, like levothyroxine (Synthroid), will replace your missing hormones if your thyroid is underactive. Fine-tuning the dosage is the key here.
Doctors say that before the most recent TSH blood test was developed in the 1970s, thyroid medications were often overprescribed or the prescribed dosages were not correct. Then or now, taking too much levothyroxine can result in problems such as loss of bone mass or atrial fibrillation, which increases stroke risk. For these reasons, experts recommend that you be alert to any changes you experience with such medications and consult your doctor with concerns.
It's imperative, too, to take your levothyroxine correctly. The Food and Drug Administration advises strict adherence to taking the drug on an empty stomach once a day (at approximately the same time each day) and waiting 30 to 60 minutes before eating or drinking.
For the much less common problem of hyperthyroidism, you will be referred to an endocrinologist, who will lay out one of several treatments to reduce your thyroid's overproduction of hormones. The first option is an Rx for thionamides or other doctor-prescribed medications to reduce overproduction of hormones. The second is a radioactive iodine therapy. In that case you'll take a capsule or drink containing iodine as well as a low dose of radiation that destroys cells in the thyroid, reducing the amount of hormones it can produce. In extreme cases, surgery to remove all or part of your thyroid gland may be recommended.