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Quick Facts



The Manual's Editorial Staff

Last full review/revision Jul 2020| Content last modified Jul 2020
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Your thyroid is a gland below the Adam’s apple in the front of your neck.

Your thyroid releases thyroid hormones. The hormones control how fast your body’s chemical functions work (metabolic rate). Almost every cell in your body needs thyroid hormones. Among many other things, thyroid hormones help control:

  • How fast you burn calories

  • How fast your heart beats

  • Your body temperature

Locating the Thyroid Gland

Locating the Thyroid Gland

What is hyperthyroidism?

"Hyper" means too much. So hyperthyroidism is when your thyroid is too active and makes more thyroid hormone than your body needs.

  • Symptoms include a fast heart rate, high blood pressure, and weight loss

  • Blood tests can confirm you have hyperthyroidism

  • Medicines can usually help with hyperthyroidism

  • Hyperthyroidism happens in about 1 out of every 100 people

Thyroid storm is very severe hyperthyroidism that happens when your thyroid suddenly releases a dangerous amount of hormones. It's usually brought on by an infection, heart attack, stroke, surgery, or extreme stress. It's an emergency that can be fatal if not treated quickly.

What causes hyperthyroidism?

The most common causes include:

  • Graves disease

  • Thyroid inflammation (thyroiditis)

  • Growths (nodules) in your thyroid

  • Certain medicines

In Graves disease, your body's immune system mistakenly attacks the thyroid (an autoimmune disease). Most autoimmune diseases make things stop working. But in Graves disease, the attack by your immune system makes your thyroid work harder and make more thyroid hormones.

Thyroiditis results from certain viral infections and other diseases that inflame your thyroid. Damaged cells in the inflamed thyroid can release extra thyroid hormones.

Thyroid nodules are small growths that often result from a genetic disease. Some nodules release thyroid hormones. Thyroid cancers also are small growths, but they rarely produce thyroid hormones.

What are the symptoms of hyperthyroidism?

Symptoms of hyperthyroidism usually involve a speeding up of body functions. So you might have:

  • High blood pressure

  • Fast heart rate and palpitations (sensation of unusual heart beats)

  • A lot of sweating and a feeling of being very warm all the time

  • Shaky hands

  • Nervousness, anxiety, and difficulty sleeping

  • Weight loss

  • Frequent bowel movements, sometimes with diarrhea

  • In women, irregular or no menstrual periods

Some diseases that cause hyperthyroidism make your thyroid swell or hurt.

Older people with hyperthyroidism may have less obvious symptoms. Symptoms in older people may include:

  • Weakness

  • Confusion

  • Weight loss

  • Depression

People with Graves disease can have problems with their eyes including:

  • Eyes that bulge

  • Red eyes

  • Dry eyes

  • Sometimes, blurry vision or seeing double

Thyroid storm

Symptoms of thyroid storm are the same as those of regular hyperthyroidism but more severe, including:

  • High fever

  • Extreme weakness

  • Restlessness and confusion

  • Passing out

  • Shock (a dangerous drop in blood pressure)

How can doctors tell if I have hyperthyroidism?

Doctors will do:

How do doctors treat hyperthyroidism?

Treatment depends on the cause of the hyperthyroidism.

Doctors will treat you with:

  • Medicines, such as beta blockers, to control symptoms

  • Medicines to keep your thyroid from making thyroid hormones

Sometimes, doctors need to permanently stop your thyroid from making any more hormones. They may stop your thyroid by:

  • Doing surgery to remove part or all of your thyroid

  • Giving you high doses of radioactive iodine, which will destroy the thyroid

After you've had surgery or radioactive iodine treatments, you'll need to take thyroid hormone pills because your body no longer makes its own thyroid hormones.

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