What Does Your Thyroid Do?

Medically Reviewed by Sanjay Ponkshe, MD on April 27, 2025
5 Amazing Facts About Your ThyroidThis small gland in your neck has a big job. How’s it like a call center? And what’s its connection with iodine? 75

SPEAKER: The thyroid might be

small, but it's got a big job.

Here are five amazing facts

about the thyroid.

The thyroid acts like a call

center for your body,

sending messages in the form

of hormones to your blood.

These hormones deliver messages

about things like how calories

are used and how much oxygen you

need.



The thyroid helps your brain

work.

If you feel forgetful, spaced

out, or have constant brain fog,

like forgetting where you put

your car keys,

check with your doctor.

You could have

an underactive thyroid.

Other symptoms could be fatigue,

weight gain, and hair loss.



Would you believe

that a healthy thyroid is just

a little bigger than a quarter?

It's also shaped

like a butterfly and is located

in the front of your lower neck.



Sudden, unexpected weight loss

can point

to an overactive thyroid.

Other signs include hot flashes,

poor sleep, or feeling nervous.

But the most unique sign

for an underactive thyroid

may be losing hair

on the outer edge

of your eyebrows.



Did you know that they put

iodine in our table salt

to help with our thyroids?

Before the 1920s,

there were so many people not

getting enough iodine,

they called big parts of North

America the "goiter belt."



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The thyroid is a 2-inch-long, butterfly-shaped gland in the front of your neck that controls your metabolism. It’s part of your endocrine system, which makes chemicals called hormones that help control many of your body’s functions.

The thyroid sits just below your voice box (larynx), near the base of your neck. Two hormones made by the thyroid gland help regulate your metabolism -- the chemical processes in your body that break down what you eat to make energy. They can affect how fast your heart beats, how deep you breathe, and whether you gain or lose weight. They can also help control your body temperature, cholesterol levels, and women’s menstrual cycles.

Doctors call these hormones T-3 and T-4 for short. The thyroid releases them into your bloodstream, which takes them through your body. Another gland, called the pituitary gland, tells your thyroid how much of these hormones your body needs.

Sometimes, the thyroid gland develops a problem. It might start producing too much or too little hormone. It might become enlarged, or it could grow lumps of extra tissue.

More than 12% of people will have some sort of problem with their thyroid during their lifetime. Women are far more likely to have this happen than men.

Common thyroid problems include:

Hypothyroidism. This occurs when your thyroid doesn’t make enough hormones. That slows your metabolism. It can make you gain weight and feel sluggish or depressed. Sometimes that’s caused by a condition called Hashimoto’s disease. This happens when your body’s disease-fighting immune system attacks the thyroid.

Hyperthyroidism. If you’re feeling irritable, losing weight, your heart races, and you’re feeling weak, your thyroid might be producing too much hormone. This is often the result of another immune system problem, known as Graves’ disease, but can be caused by other conditions as well.

Goiters. A goiter happens when your thyroid gland swells up. Sometimes, it makes a noticeable bulge in your neck; other times, it can make you cough or make your voice sound hoarse. A goiter can be caused by other thyroid conditions or by a lack of iodine, an element your thyroid needs to work properly. Most Americans get plenty of iodine because it’s now added to table salt in the United States.

Nodules. These are growths on the thyroid gland. Sometimes, they can cause the thyroid to make too much hormone -- and in some cases, they turn out to be cancerous.

If you’re experiencing any of these things, talk to your doctor. They can order some tests to help pinpoint the problem and discuss ways to treat it.

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