- The thyroid is a small gland that can have a big impact on your body.
- Via hormone production, your thyroid can affect your weight, body temperature, mood, and more.
- Millions of Americans have thyroid conditions, including many celebrities who have opened up about it.
- Visit Insider’s homepage for more stories.
If you’ve never had to worry about your thyroid, you probably don’t know much about it. But this small part of your body can have a big impact if something goes wrong.
Here are all the facts you need to know about this enigmatic piece of anatomy.
Your thyroid is a butterfly-shaped gland that sits in your neck.
“The thyroid is a small gland,” Dr. Betul Hatipoglu, an endocrinologist at Cleveland Clinic, told Insider. “It is the shape of a butterfly and it sits on the lower part of our neck, near our collarbone.”
You can’t feel a normal-sized thyroid.
The average thyroid is about two inches wide, according to the US National Library of Medicine. A normal thyroid can’t be seen and can barely be felt, according to the Merck Manual. Certain conditions can cause the thyroid to swell (called goiter) or to form nodules, which a doctor may be able to see or feel through the skin.
Your thyroid accomplishes its work through hormones.
According to the USNLM, the thyroid produces three hormones: triiodothyronine (T3), tetraiodothyronine (T4, or thyroxine), and calcitonin. T3 and T4 accomplish most of the functions directed by the thyroid, while calcitonin affects calcium and bone metabolism.
Experts often refer to the three collectively as “thyroid hormone.”
“[Thyroid hormone] is a signal that travels throughout the body that regulates how the body uses energy and essentially affects every other organ system,” Dr. Elizabeth Pearce, an endocrinologist at Boston Medical Center and president-elect of the American Thyroid Association, told Insider.
The pituitary gland controls the thyroid.
The pituitary, a peanut-sized gland known for its role in puberty, regulates the thyroid. “The pituitary gland ‘tells’ the thyroid gland whether to release more or less hormones into the bloodstream,” using the aptly-named thyroid-stimulating hormone, according to the USNLM.
Abnormal levels of TSH may indicate that your thyroid is producing too much or too little thyroid hormone, according to the Merck Manual. TSH testing is the easiest and most accurate way to see if your thyroid is working irregularly.
Your thyroid affects a lot more than your energy level.
Broadly speaking, thyroid hormone regulates chemical functions in virtually every tissue in your body, either by stimulating cells to produce certain proteins or increasing the amount of oxygen they use, according to the Merck Manual.
Thyroid hormone affects heart rate, metabolism, skin maintenance, growth, body temperature, digestion, and fertility, and more.
The thyroid acts as your body’s furnace.
Your body temperature is increased when more thyroid hormones are produced, according to the USNLM. The pituitary is the thermostat, telling the thyroid when to turn on or shut off according to the body’s current temperature. That’s why people with thyroid disorders may feel hotter or colder than others.
Your thyroid stores extremely concentrated amounts of hormones.
In a post for Mental Floss Dr. Linda Anegawa wrote that the thyroid “can store a very large amount of hormone— so much that if the gland released all of its hormone into the bloodstream at once, it could kill you.”
This rare condition is known as thyroidtoxicosis. Not to worry — Anegawa wrote that the “thyroid hormone is very tightly regulated by constant, exquisitely sensitive signals traveling between the brain, the gland, the body’s tissues, and the blood concentrations of the hormone at any given moment.”
Over 20 million Americans have some form of thyroid disease, according to the ATA.
And more than 12% of the US population will develop a thyroid condition in their lifetime, with up to 60% of those people being unaware of their condition. The American Thyroid Association website also states that most causes of thyroid conditions are unknown. But, these conditions can be managed with the help of a doctor.
“There are a few different types of thyroid disease,” Pearce said. “The thyroid function can get out of whack, so you can either make too much thyroid hormone, which is hyperthyroidism, or you can make too little thyroid hormone, which is hypothyroidism. Or the other major issue that can happen is thyroid enlargement, which comes from the development of lumps, nodules, or thyroid cancer.”
Sudden fatigue and weight gain could be signs of an underactive thyroid, according to the USNLM.
Depression, constipation, sensitivity to cold, heavy periods, concentration problems, dry skin, hair loss, and reduced sweating are also symptoms of underactive thyroid, or hypothyroidism. Unfortunately, these symptoms have multiple potential causes, so it’s best to check with your doctor if you’re experiencing any of them. They may decide to check the thyroid hormone and TSH levels in your blood to screen for a thyroid condition.
“All of the symptoms of thyroid disorders are so nonspecific because, again, it affects the whole body,” Pearce said. “If people have symptoms that are suggestive of hyper- or hypothyroidism, it’s easy to diagnose with a blood test to figure out if thats really the case. And if it’s not, they should look for other causes.”
A pounding heart, excessive sweating, and insomnia might signal an overactive thyroid, according to the USNLM.
Other signs of hyperthyroidism include diarrhea, nervousness, trembling, and sensitivity to heat. Again, these symptoms can be caused by a variety of conditions, so check with your doctor if you experience them. About 1 in 100 people have an overactive thyroid, according to the USNLM.
Thyroid cancer is on the rise.
The American Cancer Society website describes thyroid cancer as “the most rapidly increasing cancer” in the US. This is partly because doctors are catching it more often.
“Often the [cancerous] thyroid nodules are found when people are getting imaging for other disorders,” Pearce said. “Just the fact that we’re doing so much more imaging today than we were doing a couple of decades ago probably is the largest driver of why the cancer prevalence has increased.”
The good news is that thyroid cancer is not a very deadly cancer.
“This is not a cancer that really kills people,” Hatipoglu said. “We are able to catch them, treat them, and cure them most of the time. I’m not saying that it never kills anybody, but it is very rare.”
But if you notice any thyroid cancer symptoms — a lump, swelling, or pain in the neck, hoarseness, trouble swallowing or breathing, or a constant cough — you should get checked out by a doctor.
Thyroid issues are more common in women.
Thyroid disorders are almost eight times more common in women than in men, Hatipoglu said.
Autoimmune disorders are more common in women, Pearce explained, and often, thyroid dysfunction is caused by autoimmune disorders. In fact, in the US, two autoimmune conditions — Graves’ disease and Hashimoto’s disease — are the most common causes of hyper- and hypothyroidism, respectively, according to the US Department of Health and Human Services Office on Women’s Health. In these conditions, the immune system mistakenly attacks the thyroid.
But both Pearce and Hatipoglu said we still don’t know the exact reasons why more women are plagued by more autoimmune and thyroid problems.
Iodine is an important nutrient for thyroid health.
If you don’t get enough iodine, your thyroid can become enlarged, according to the ATA. You can get iodine in your diet by using iodized table salt, or eating foods that are naturally rich in the nutrient, including dairy products, seafood, meat, some breads, and eggs. It’s also in some multivitamins.
You likely don’t have to worry about your iodine intake. Pearce explained that iodine deficiency hasn’t been common in the US since the 1940s. But she did note that “mild iodine deficiency” has started to emerge in the last decade or so, specifically among pregnant women, who need more iodine than the general population.
“That matters because even mildly low iodine deficiency during pregnancy can be associated with lower IQ in children,” Pearce said. Because of this, the ATA recommends that all pregnant and breastfeeding women in the US take a daily prenatal multivitamin containing 150 micrograms of iodine.
You can try checking your thyroid at home, but you’re better off having a doctor do it.
Pearce explained that there’s no national recommendation for people to self-check their thyroid at home, and that there’s no evidence doing self-checks is associated with better health outcomes in the future.
Instead, she suggested keeping your regular primary care doctor’s visits.
“The doctor should just put a hand on the front of the neck and often thyroid enlargement can be picked up pretty readily that way,” she said. “And people who are particularly high risk for thyroid cancers, like people who have family history of thyroid cancer or people who have a history of head or neck radiation treatments, should discuss with their providers whether they need additional screening.”
If you do want to try checking your thyroid at home, the video above from the Cleveland Clinic shows you how to do it.
Certain celebrities are open about their thyroid conditions.
Several celebrities have opened up about their experiences with thyroid conditions. Gigi Hadid has been candid about being diagnosed with Hashimoto’s disease, and Wendy Williams disclosed that she was diagnosed with Grave’s disease in 2018. According to Fox News, other celebrities who have thyroid-related diagnoses include former President George H.W. Bush, Kim Cattrall, Missy Elliott, Kelly Osbourne, and Jillian Michaels.
Medications can affect your thyroid function.
According to a review published in 2015, select medications can increase or decrease thyroid function or the amount of thyroid hormone in the body. These medications include but are not limited to Amiodarone, Glucocorticoid, Iodide, Lithium, and Phenytoin.
If you’re taking one of these medications, talk to your doctor and pharmacist about how it may be affecting your thyroid.
Synthetic thyroid hormone is one of the top drugs dispensed in the United States.
Levothyroxine (brand names Synthroid, Unithroid, Levoxyl, and Levothroid) is a synthetic thyroid hormone used to treat hypothyroidism. According GoodRx’s August 2020 list of the 10 most popular prescription drugs based on pharmacy claims data, levothyroxine is the fourth-most dispensed medication in the US.
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