What is hyperthyroidism?


Hyperthyroidism: Overview

Hyperthyroidism occurs when the thyroid gland makes too much thyroid hormone. This speeds up your metabolism—how your body uses energy. This condition can cause you to be very active, lose weight, and have sleep problems, eye problems, and a fast heart rate. It can also cause a goiter. A goiter is an enlarged thyroid gland that you can see at the front of the neck.

Hyperthyroidism is often caused by Graves' disease. In Graves' disease, the body's defense (immune) system attacks the thyroid gland.

Your doctor may prescribe a beta-blocker medicine to slow your pulse and calm you down. But this is not a treatment for hyperthyroidism. It is given for your fast heart rate. Your doctor may also give you antithyroid medicine. This medicine keeps excess thyroid hormone in check. In some cases, doctors recommend radioactive iodine or surgery to remove the thyroid. After either of these treatments, you may need to take medicine to replace thyroid hormone for the rest of your life.


Hyperthyroidism means that your body has too much thyroid hormone, which controls how your body uses energy. Too much thyroid hormone can make you lose weight quickly, have a fast heartbeat, sweat a lot, or feel nervous and moody. If it isn't treated, it can cause serious problems.

What are the symptoms of hyperthyroidism?

You may have no symptoms of hyperthyroidism. Or, you may feel nervous, moody, weak, or tired. Other symptoms include shaking hands, feeling hot and sweaty, and losing weight, even if you are eating normally.

How is hyperthyroidism treated?

Radioactive iodine is the most common treatment for hyperthyroidism. Most people are cured after taking one dose. It destroys part of your thyroid gland. Antithyroid medicine pills may be prescribed if your symptoms are mild. If they stop working, you may need to try radioactive iodine.

How is radioactive iodine used to treat hyperthyroidism?

Radioactive iodine is given as a liquid or capsule that you swallow. The iodine is taken up by your thyroid gland. The radioactivity in the iodine kills most or all of the tissue in your thyroid gland. But it doesn't harm any other parts of your body.

Most people are cured of hyperthyroidism after one dose of the medicine.

Radioactive iodine damages your thyroid gland. Over time, most people who take it develop hypothyroidism (having too little thyroid hormone). If you have hypothyroidism, you can replace the thyroid hormone by taking thyroid hormone medicine for the rest of your life.

Radioactive iodine shouldn't be used by children. And it shouldn't be used by women who:

  • Are pregnant.
  • Are breastfeeding.
  • Want to become pregnant within 6 months of treatment.

How is hyperthyroidism diagnosed?

Your doctor will ask questions about your past health and your symptoms and will do a physical exam to diagnose hyperthyroidism. If your doctor thinks you may have the condition, he or she will order blood tests to see how much thyroid hormone your body is making.

How are medicines used to treat hyperthyroidism?

Antithyroid medicine is often used for hyperthyroidism. It works faster than radioactive iodine therapy. And unlike radioactive iodine, it doesn't cause lasting thyroid damage.

You also may take this medicine before you have radioactive iodine treatment or surgery. Taking it may bring your metabolism to normal, make you feel better, or reduce the chances of more serious problems.

Antithyroid medicine controls hyperthyroidism in many people. But:

  • You have to take the medicine for at least 1 year.
  • Your symptoms may come back after you stop taking it. Then you have to start taking it again or try a different treatment.
  • There are some rare side effects. These include a rash and a low white blood cell count. A low white cell count can make it hard for your body to fight infection.

You may take beta-blockers or other medicines to treat symptoms such as a fast heartbeat or dry eyes until your thyroid improves.

How can you care for yourself when you have hyperthyroidism?

  • Take your medicines exactly as prescribed. You need to take the thyroid medicine at the same time each day. Call your doctor if you think you are having a problem with your medicine.
  • Graves' disease can make your eyes sore. Use artificial tears, eye drops, and sunglasses to protect your eyes from dryness, wind, and sun. Raise your head with pillows at night to prevent your eyes from swelling. In some cases, taping your eyelids shut at night will keep your eyes from being dry in the morning.
  • Make sure you get enough calcium. Foods that are rich in calcium include milk, yogurt, cheese, and dark green vegetables.
  • If you need to gain weight, ask your doctor about special diets.
  • Do not eat kelp. Kelp is high in iodine, which can make hyperthyroidism worse. Kelp is commonly used in sushi and other Japanese foods. You can use iodized salt and eat bread and seafood. Try to eat a balanced diet.
  • Do not use caffeine and other stimulants. These can make symptoms worse, such as a fast heartbeat, nervousness, and problems focusing.
  • Do not smoke. Smoking can make your condition worse and may lead to more serious eye problems. If you need help quitting, talk to your doctor about stop-smoking programs and medicines. These can increase your chances of quitting for good.
  • Lower your stress. Learn to use biofeedback, guided imagery, meditation, or other methods to relax.
  • Use creams or ointments for irritated skin. Ask your doctor which type to use.
  • Tell all your doctors about your condition. They need to know because some medicines contain iodine.

How is surgery used to treat hyperthyroidism?

Surgery for hyperthyroidism is called thyroidectomy. It removes part or all of the thyroid gland. Doctors rarely use this surgery to treat hyperthyroidism. It's riskier than other treatments.

You may need surgery if:

  • Your thyroid gland is so big that it's hard for you to swallow or breathe.
  • You have thyroid cancer.
  • Your doctor suspects that you have thyroid cancer.
  • You had serious side effects from taking antithyroid medicines, and radioactive iodine isn't an option for you.
  • You have a large goiter that radioactive iodine treatment didn't shrink.
  • You have a single, large thyroid nodule that makes too much thyroid hormone, and radioactive iodine didn't help with the nodule.

Your doctor will have you take antithyroid medicines if you have any surgery for the condition.

After surgery, your doctor will check your thyroid hormone levels regularly. That's because you could get hypothyroidism (too little thyroid hormone).

What are some complications of hyperthyroidism?

Graves' ophthalmopathy is one complication of hyperthyroidism. People with this condition develop eye problems, including bulging, reddened eyes. In rare cases, hyperthyroidism can cause a life-threatening condition called thyroid storm. This happens when the thyroid gland releases large amounts of thyroid hormones in a short period of time.

What causes hyperthyroidism?

Graves' disease causes most hyperthyroidism. In Graves' disease, the body's natural defense (immune) system attacks the thyroid gland. The thyroid reacts by making too much thyroid hormone. Graves' disease often runs in families. Sometimes hyperthyroidism is caused by a swollen thyroid or small growths in the thyroid called thyroid nodules.

What is hyperthyroidism?

Hyperthyroidism means your thyroid gland makes too much thyroid hormone. Thyroid hormone controls how your body uses energy, also called metabolism. When you have too much thyroid hormone, your metabolism speeds up. You may lose weight quickly or feel nervous and moody. Or you may have no symptoms at all.

Hyperthyroidism: When to call

Call your doctor now or seek immediate medical care if:

  • You have symptoms of a sudden, very high thyroid level (thyroid storm). These include:
    • Being nauseated, vomiting, and having diarrhea.
    • Sweating a lot.
    • Feeling extremely restless and confused.
    • Having a high fever.
    • Having a fast heartbeat.
  • You have sudden vision changes or eye pain.
  • You have a fever or severe sore throat and are taking antithyroid medicines, such as PTU or methimazole.

Watch closely for changes in your health, and be sure to contact your doctor if:

  • You have a sore throat or have problems swallowing.
  • You have swollen, itchy, or red eyes or your other eye symptoms get worse, or you have new vision problems.
  • You have signs of a low thyroid level (hypothyroidism). You may feel very tired, confused, or weak.

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