Your thyroid gland plays a role in nearly every bodily process. Learn how it works—plus the signs that something may be amiss.
Your heart and brain get all the attention, but your thyroid—that butterfly-shaped gland situated below your voice box and above your collarbone—is the true unsung hero of your body. It produces two main hormones, triiodothyronine (T3) and thyroxine (T4), that travel in your bloodstream, influencing physiological functions from head to toe. “Every cell in your body needs thyroid hormones to work correctly,” says J. Woody Sistrunk, MD, a member of the American Thyroid Association’s board of directors. “They regulate everything from metabolism to bone health. So much depends on your thyroid being perfect.”
When it’s not, problems arise. If your thyroid gland is underactive, for example—a condition known as hypothyroidism levels of T3 and T4 can sink too low; because the hormones influence neurological function, you might feel forgetful or depressed. If your thyroid is overactive, a condition called hyperthyroidism, T3 and T4 creep too high, and you may experience irritability or anxiousness, explains Dr. Sistrunk. Hyperthyroidism can also speed up your metabolism, and may lead to weight loss, while hypothyroidism can cause weight gain.
A thyroid dysfunction can throw off your menstrual cycle, too, and might explain peekaboo periods. Your thyroid even affects the regularity of your No. 2s: Hypothyroidism is linked to constipation, and hyperthyroidism can bring on frequent, loose BMs.
There’s a risk of more serious health issues as well. When thyroid hormones climb too high, the body destroys old bone faster than it can be replaced, which hastens osteoporosis. An overactive thyroid can also trigger the heart rhythm disorder atrial fibrillation. An underactive thyroid, on the other hand, can make you more prone to high cholesterol and complications with your blood pressure.
But the biggest tip-off that your thyroid isn’t functioning right is feeling “wiped,” says Shirisha Avadhanula, MD, an endocrinologist at the Cleveland Clinic. “You’re so tired that you’re not able to carry out your daily tasks or get through your normal workout routine.” And the tiredness doesn’t go away after a good night’s rest. That kind of overwhelming fatigue is a symptom of both hypo- and hyperthyroidism.
Just being a woman raises your likelihood of developing a thyroid problem. Why that is remains somewhat of a mystery. “Estrogen definitely plays a role in some way,” says Terry Davies, MD, the codirector of Mount Sinai’s Thyroid Center in New York City. “Thyroid cells have a lot of estrogen receptors,” he explains, which would make them especially sensitive to the effects of the female hormone.
There’s also the fact that many thyroid conditions are autoimmune disorders. The most common cause of an underactive thyroid, for example, is Hashimoto’s disease, while the most common cause of an overactive thyroid is Graves’ disease. And those are more likely to affect women too. Your genes may factor in as well: A 2017 study in the journal Clinical Thyroidology for the Public found that almost half of Hashimoto’s patients have a family history of the disease.
The good news is, most thyroid disorders are treatable once you have a diagnosis. Your doctor can get a picture of what’s going on with an exam and a blood test that measures your level of TSH—or thyroid-stimulating hormone. This hormone is released by your pituitary gland to trigger the thyroid to produce T3 and T4.
In people with hypothyroidism, the thyroid gland doesn’t respond well to TSH, and the pituitary gland churns out more and more of the hormone in an effort to stimulate the release of T3 and T4. Conversely, when the thyroid is in overdrive, your brain senses that levels of T3 and T4 are too high, and the pituitary gland makes little to no TSH.
If your doc diagnoses you with hypothyroidism, she will prescribe a synthetic form of thyroid hormone called levothyroxine. This medication, which you take once a day, is considered very safe, says Dr. Sistrunk; at the right dose, you should have minimal or no side effects.
With hyperthyroidism, the first line of treatment is usually the drug methimazole, which stops the thyroid from pumping out too much of the hormones, Dr. Sistrunk says. But because there are some concerns with using antithyroid drugs during pregnancy, if you’re planning on having children at some point, you might consider having your thyroid removed instead, or taking radioactive iodine, which gradually shrinks the gland and ultimately destroys it. Once your thyroid is gone, you’ll need to take levothyroxine for life.
One thing you can do to help keep your thyroid healthy is make sure you have a good source of iodine in your diet. The mineral is a critical raw material for the production of T3 and T4. Most people consume enough iodine since it’s in fortified foods, such as breads, as well as iodized table salt—just ½ to ¾ of a teaspoon will get you to the daily target of 150 mcg. But if you are on a very-low-salt diet or only cook with sea salt, or you’re gluten-free, you might need to focus on other sources, says Dr. Sistrunk. Eggs, dairy, saltwater fish, and seaweed can all help you meet the requirement. People with hypo- or hyperthyroidism don’t need to consume more or less iodine than the recommended amount; there’s no evidence that the mineral can actually treat those conditions, and excessive amounts may worsen them.
If you suspect your thyroid needs a boost, you may be curious about the many “thyroid support” supplements sold in drugstores and online. These pills promise to increase your energy, rev your metabolism, and more. But they’re risky, warns Dr. Avadhanula.
When Mayo Clinic researchers analyzed 10 popular products, they discovered that nine of them actually contained T3 or T4, or both—and some of the supplements supplied doses that were equal to or higher than the amount of synthetic thyroid hormone a doctor might prescribe. Such a dose could cause serious side effects, including bone-mass loss or an irregular heartbeat.
Bring your thyroid concerns up with your doc before you experiment with an over-the-counter pill. She’ll help you identify the underlying problem, so you get a remedy that’s effective and safe. “Your thyroid is the engine that powers your entire body,” says Dr. Avadhanula. “With a little teamwork, you and your physician can make sure it’s right on track.”
Is thyroid cancer becoming more common?
In the past 30 years, diagnoses of thyroid cancer have tripled. But the spike isn’t as alarming as it sounds, says Mark Zafereo, MD, a thyroid cancer surgeon at MD Anderson Cancer Center in Houston.
Doctors are using ultrasound and other neck imaging more often, he explains: “Studies suggest much of the increase in diagnoses is due to incidental findings of small, slow-growing cancers that may not have been diagnosed in decades past.” In fact, he adds, there are many women walking around with such tumors who may never need treatment.
If your doc detects a nodule that’s less than a centimeter, she’ll likely track it to see if it’s growing, says Jessica Geiger, MD, an oncologist at the Cleveland Clinic. (About 90 percent to 95 percent of nodules are benign.) With a larger cancerous nodule, depending on the size, the protocol is to have part or all of your thyroid surgically removed; after that, you’ll take a daily dose of the synthetic thyroid hormone replacement medication levothyroxine.
There’s unfortunately not much you can do to reduce your odds of thyroid cancer, says Dr. Zafereo. “Over 95 percent of the time, there’s no associated risk factor—we just consider these cancers random genetic events.”