Myth vs Fact

What Does the Thyroid Gland Do?

  • Editors
  • Bryan Haugen, MD

    James V. Hennessey, MD

    Leonard Wartofsky, MD

The thyroid (THY-royd) gland, a small butterfly-shaped gland in the front of your neck, makes thyroid hormones. Thyroid hormones travel from the thyroid gland through the blood to all parts of the body, where they do their work.

Why are thyroid hormones important?

Thyroid hormones help all your organs work well. They control how your body uses food for energy.

What Do Thyroids DoThyroid hormones affect your metabolism rate, which means how fast or slow your brain, heart, muscles, liver, and other parts of your body work.

If your body works too fast or too slowly, you won’t feel well. For example, if you don’t have enough thyroid hormone, you might feel tired and cold. Or, if you have too much thyroid hormone, you might feel nervous, jumpy, and warm.

How does the thyroid gland work?

Your thyroid gland is controlled by the pituitary (pah-TOO-ah-tare-ee) gland, a pea-sized gland located at the base of your brain. The pituitary gland keeps checking the amount of thyroid hormone in your blood. Then it tells your thyroid to make more or less hormone so there’s always the right amount.

Your thyroid uses iodine to make thyroid hormone. Iodine comes from food, mainly seafood and dairy products. It is also added to salt since it can be hard to get enough from food.

Your thyroid gland is located in the front of your neck.

Words to Know

endocrinologist (EN-doh-krih-NOLL-uh-jist): a doctor who treats people who have endocrine gland problems or hormone problems such as thyroid problems.

endocrine (EN-doh-krin) gland: a group of cells that makes hormones and sends them into the blood to have effects on other cells.

goiter (GOY-ter): an enlarged thyroid

hormone (HOR-mohn): a chemical made in an endocrine gland in one part of the body. The hormone is sent through the blood to another part of the body, where it helps other cells do their job.

hypothyroidism (hi-poh-THY-royd-izm): when your thyroid gland doesn’t make enough thyroid hormone (“hypo” means ‘under’ or ‘below’).

hyperthyroidism (hi-purr-THY-royd-izm): when your thyroid gland makes too much thyroid hormone (“hyper” means ‘over’ or ‘above’).

metabolism (meh-TAB-oh-lizm): how your body breaks down food, uses it for energy, or stores it for later use.

What can go wrong with my thyroid?

A few things can go wrong. But you can get treatment to fix thyroid problems. Anyone—even babies—can have thyroid problems.

Having thyroid hormone levels that are too low (underactive thyroid gland)

Sometimes the thyroid gland doesn’t make enough thyroid hormone, which is called hypothyroidism. When you don’t have enough thyroid hormone, parts of your body work too slowly.

Symptoms of underactive thyroid include

Having thyroid hormone levels that are too high (overactive thyroid gland)

Sometimes the thyroid gland makes too much thyroid hormone, which is called hyperthyroidism. Think of your body as a car and your thyroid as the engine. An overactive thyroid makes your body idle too fast.

Symptoms of overactive thyroid gland include

Having a lump in your thyroid gland

You can have a lump or swelling in your thyroid gland, called a nodule (NOD-jule). Nodules may have no effect on how the gland works, or can lead to too much thyroid hormone. Most nodules are benign (not cancer), but some can be cancerous.

Having an enlarged thyroid gland

When your thyroid is enlarged (called a goiter [GOY-ter]), it can produce too much, not enough, or just the right amount of thyroid hormone. Your doctor will try to find out why your thyroid is enlarged.

Can I live without my thyroid?

Yes. If your doctor needs to remove your thyroid, you can stay healthy by taking a thyroid hormone pill every day.

Questions to ask your doctor

Where to learn more