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what does
the Thyroid Gland Do?
The thyroid (THY-royd) gland, a small butterflyshaped 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.
Thyroid gland
Thyroid 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.
Your thyroid gland is located
in the front of your neck.
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.
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
• Feeling tired
• Feeling cold even when other people
are comfortable or even warm
• Having a slow heart rate and dry skin
• Being constipated
• Gaining weight even though you’re not
eating more or exercising less than usual
• In children, growing very slowly
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
• Feeling nervous and irritable
• Having trouble concentrating
• Feeling too warm even when other
people don’t feel warm
• Having a fast heart rate and diarrhea
• Having trouble sleeping
• Losing weight without trying
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
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
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
What’s wrong with my thyroid?
Do I need more tests?
What treatment do I need?
How long will I need the treatment?
your thyroid gland makes too much thyroid
hormone (“hyper” means ‘over’ or ‘above’).
Does the treatment have side
effects?
metabolism (meh-TAB-oh-lizm): how your body
breaks down food, uses it for energy, or stores it
for later use.
How often should I have check-ups?
Should I see an endocrinologist for
my care?
Where to Learn More
Hormone Health Network thyroid information: www.hormone.org/Thyroid/thyroid.cfm
National Institutes of Health information:
• Thyroid disease (MedlinePlus): www.nlm.nih.gov/medlineplus/thyroiddiseases.html
• Underactive thyroid: www.endocrine.niddk.nih.gov/pubs/hypothyroidism/
• Overactive thyroid: www.endocrine.niddk.nih.gov/pubs/hyperthyroidism/index.aspx
To find an endocrinologist near you:
www.hormone.org or call 1-800-HORMONE (1-800-467-6663)
Editors Bryan Haugen, MD, James V. Hennessey, MD, Leonard Wartofsky, MD
What Does the Thyroid Gland Do? November 2012
www.hormone.org