Hyperthyroidism

	Topic Overview
	Health Tools
	Cause
	Symptoms
	What Happens
	What Increases Your Risk
	When To Call a Doctor
	Exams and Tests
	Treatment Overview
	Prevention
	Home Treatment
	Medications
	Surgery
	Other Treatment
	Other Places To Get Help
	Related Information
	References
	Credits
	Audio articles:
	English
	Español

What is hyperthyroidism?

Hyperthyroidism means your thyroid makes too much thyroid hormone. Your thyroid is a gland in the front of your neck. It controls your metabolism, which is how your body turns food into energy. It also affects your heart, muscles, bones, and cholesterol.

Having too much thyroid hormone can make a lot of things in your body speed up. You may lose weight quickly, have a fast heartbeat, sweat a lot, or feel nervous and moody. Or you may have no symptoms at all. Your doctor may discover that you have hyperthyroidism while doing a test for another reason.

Hyperthyroidism is easily treated. With treatment, you can lead a healthy life. Without treatment, hyperthyroidism can lead to serious heart problems, bone problems, and a dangerous condition called thyroid storm.

What causes hyperthyroidism?

Graves' disease causes most hyperthyroidism. In Graves’ disease, the body's natural defense (immune) system attacks the thyroid gland. The thyroid fights back by making too much thyroid hormone. Like many thyroid problems, it often runs in families.

Sometimes hyperthyroidism is caused by a swollen thyroid or small growths in the thyroid called thyroid nodules.

This topic focuses on hyperthyroidism caused by Graves' disease.

What are the symptoms?

You may have no symptoms at all. Or:

• You may feel nervous, moody, weak, or tired.
• Your hands may shake, your heart may beat fast, or you may have problems breathing.
• You may be sweaty or have warm, red, itchy skin.
• You may have more bowel movements than usual.
• You may have fine, soft hair that is falling out.
• You may lose weight even though you eat the same or more than usual.

If you have any of these symptoms, call your doctor. Without treatment, hyperthyroidism can lead to heart problems, bone problems, and a dangerous condition called thyroid storm.

How is hyperthyroidism diagnosed?

Your doctor will ask you about your symptoms and do a physical exam. Then he or she will order blood tests to see how much thyroid hormone your body is making.

Sometimes hyperthyroidism is found while you are having a test for another reason. You may be surprised to find out that you have this problem.

How is it treated?

If your symptoms bother you, your doctor may give you pills called beta-blockers. These can help you feel better while you and your doctor decide what your treatment should be. Even if your symptoms do not bother you, you still need treatment, because hyperthyroidism can lead to more serious problems.

Radioactive iodine and antithyroid medicine are the treatments doctors use most often. The best treatment for you will depend on a number of things, including your age. Some people need more than one kind of treatment.

• Radioactive iodine is the most common treatment. Most people are cured after drinking one dose. It destroys part of your thyroid gland, but it does not harm any other parts of your body.
• Antithyroid medicine works best if your symptoms are mild. These pills do not damage your thyroid gland. But they do not always work, and you have to take them at the same time every day. If they stop working, you may need to try radioactive iodine.

After treatment, you will need regular blood tests. These tests check to see if your hyperthyroidism has come back. They also check to see if you are making enough thyroid hormone. Sometimes treatment cures hyperthyroidism but causes the opposite problem—too little thyroid hormone. If this happens, you may need to take thyroid hormone pills for the rest of your life.

Frequently Asked Questions

Health Tools help you make wise health decisions or take action to improve your health.

	Decision Points focus on key medical care decisions that are important to many health problems.
	Hyperthyroidism: Should I use antithyroid medication or radioactive iodine?

Graves' disease is the most common cause of hyperthyroidism. Graves' disease causes the thyroid gland to make too much thyroid hormone. Graves' disease, like many thyroid problems, often runs in families.

Other common causes include:

• Thyroid nodules. Thyroid nodules are abnormal growths in the thyroid gland that can make too much thyroid hormone. For more information, see the topic Thyroid Nodules.
• Thyroiditis.Thyroiditis occurs when your body makes antibodies that damage your thyroid gland. You can also get thyroiditis from a viral or bacterial infection. At first, thyroiditis may cause your thyroid levels to rise as hormone leaks out from the damaged gland. Later, levels may be low (hypothyroidism) until the gland repairs itself.

Uncommon causes of hyperthyroidism include tumors or eating foods or taking medicines that contain large amounts of iodine.

You may have hyperthyroidism if you:

• Feel nervous, moody, weak, or tired.
• Have hand tremors, or have a fast or irregular heartbeat, or have trouble breathing even when you are resting.
• Sweat a lot, and have warm, red skin that may be itchy.
• Have frequent and sometimes loose bowel movements.
• Have fine, soft hair that is falling out.
• Lose weight even though you are eating normally or more than usual.

In addition, some women have irregular menstrual cycles or stop having periods altogether, and some men may develop enlarged breasts.

The symptoms of hyperthyroidism are not the same for everyone. Your symptoms will depend on how much hormone your thyroid gland is making, how long you have had the condition, and your age. If you are older, it's easy to mistakenly dismiss your symptoms as normal signs of aging.

Specific symptoms of Graves' disease

People with Graves' disease often have additional symptoms, including:

• Goiter, which is an enlarged, painless, soft thyroid gland.
• Thickened nails that lift off the nail beds.
• Myxedema, which is lumpy, reddish, thick skin on the front of the shins and sometimes on top of the feet.
• Clubbing (fingers with wide tips).
• Graves' ophthalmopathy, which causes bulging, reddened eyes, among other symptoms.

Complications

Graves' ophthalmopathy is a frequent complication of hyperthyroidism. It can develop before, after, or at the same time as your symptoms of hyperthyroidism. People with Graves' ophthalmopathy develop eye problems, including bulging, reddened eyes, sensitivity to light, and blurring or double vision. People who smoke are more likely to develop Graves' ophthalmopathy.

If you have Graves' ophthalmopathy, it may temporarily get worse if you have radioactive iodine treatment. On the other hand, it may get better if you take antithyroid medicine.

If you do not treat your hyperthyroidism, you may:

• Lose weight because your body's metabolism is faster.
• Have heart problems such as rapid heart rate, atrial fibrillation, and heart failure.
• Have trouble replacing calcium and other minerals in your bones, which can lead to osteoporosis.

In rare cases, hyperthyroidism can cause a life-threatening condition called thyroid storm, which develops when the thyroid gland releases large amounts of thyroid hormones in a short period of time. Thyroid storm usually happens after you have had a serious infection or you have had a lot of stress in your life.

If your thyroid gland makes too much thyroid hormone, you will have symptoms of hyperthyroidism. Most hyperthyroidism is caused by an immune system problem called Graves' disease. At first, your hyperthyroidism may make you feel hot, have tremors in your hands, or lose weight. Over time, you may notice that your heart is beating fast, that you feel anxious, or that you are having a lot of bowel movements. You may also feel like you just don't have as much energy as usual.

Hyperthyroidism generally does not go away on its own. Most people need treatment to make hyperthyroidism go away. After treatment, many people develop hypothyroidism (too little thyroid hormone).

In rare cases, hyperthyroidism can cause a life-threatening condition called thyroid storm, which develops when the thyroid gland releases large amounts of thyroid hormones in a short period of time. Thyroid storm usually happens after you have had a serious infection or you have been through a stressful time in your life.

You are more likely to have hyperthyroidism if:

• You are female. Women are more likely to develop hyperthyroidism than men.
• You have a family history of thyroid problems. People who have close relatives with Graves' disease or other thyroid problems are more likely to develop hyperthyroidism.
• You have an autoimmune disease, such as Addison's disease or type 1 diabetes.
• You smoke cigarettes. People who smoke are more likely to have Graves' disease and are more likely to have Graves' ophthalmopathy.
• You have recently been through a stressful time such as a divorce or the loss of your job.

The most serious problem associated with hyperthyroidism is a life-threatening condition called thyroid storm.

Call 911 or other emergency services immediately if you have serious signs of thyroid storm such as shock or delirium.

Call your doctor immediately if you have been diagnosed with hyperthyroidism and:

• You feel very irritable.
• You have unusually high or low blood pressure.
• You feel nauseous, are throwing up, or have diarrhea.
• Your heart is beating very fast or you have chest pain.
• You have a fever.
• You are confused or feel sleepy.
• You cannot breathe well or you feel very tired, which can be symptoms of heart failure.

You should also call your doctor if:

• You develop symptoms of Graves' ophthalmopathy, such as bulging, reddened eyes.
• You feel very tired or weak.
• You are losing weight even though you are eating normally or more than usual.
• Your throat is swollen or you are having trouble swallowing.

Watchful Waiting

Watchful waiting is a period of time during which you and your doctor observe your symptoms without using medical treatment. If you think you have symptoms of hyperthyroidism, watchful waiting is not a good idea. Call your doctor if you think you may have hyperthyroidism, so you can be treated early and reduce your chances of having more serious problems.

Who To See

Health professionals who are qualified to diagnose and treat hyperthyroidism include:

• Internists.
• Pediatricians.
• Family medicine physicians.
• Nurse practitioners.
• Physician assistants.

For further treatment, your primary doctor may refer you to one of the following specialists:

• Endocrinologist
• Surgeon
• Nuclear medicine specialist
• Ophthalmologist

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Your doctor will ask questions about your medical history, do a physical exam, and order medical tests to diagnose hyperthyroidism.

If your doctor thinks you may have hyperthyroidism, he or she may order:

• A thyroid-stimulating hormone (TSH) test, which is a blood test that measures your levels of TSH. If your TSH level is low, your doctor will want to do more tests.
• Thyroid hormone tests, which are blood tests to measure your levels of two types of thyroid hormones, called T3 and T4. If your thyroid hormone levels are high, you have hyperthyroidism.

When you are being treated for hyperthyroidism, your doctor will test your TSH and thyroid hormones several times a year to see how well your treatment is working.

After you are diagnosed with hyperthyroidism, your doctor may also want to do:

• An antithyroid antibody test to see if you have the kind of antibodies that attack thyroid tissue. This test can help diagnose Graves' disease and autoimmune thyroiditis.
• A radioactive thyroid scan and radioactive iodine uptake tests, which use radiation and a special camera to determine the cause of your hyperthyroidism.

If you have Graves' ophthalmopathy, your doctor may also do an MRI and CT scan to look more closely at your eyes.

Early Detection

It is not clear whether people who do not have any risk factors and who do not have any symptoms of hyperthyroidism need to be tested regularly for thyroid problems. The American Thyroid Association recommends that adults, particularly women, be screened for thyroid problems every 5 years, beginning at age 35. But the U.S. Preventive Services Task Force does not think there is enough evidence to recommend either for or against regular thyroid testing. Talk to your doctor about whether you need to be tested for thyroid problems.

There are three treatments for hyperthyroidism. Antithyroid medication and radioactive iodine are the ones doctors use most often. In rare cases, surgery may be done. Even if your symptoms are not bothering you, you still need treatment, because hyperthyroidism can lead to more serious problems.

The kind of treatment you have depends on your age, what is causing your hyperthyroidism, how much thyroid hormone your body is making, and other medical conditions you may have. Each kind of treatment has benefits and risks. It is important to discuss the benefits and risks of each kind of treatment with your doctor. For some people, more than one kind of treatment may be necessary.

Initial treatment

Initial treatment for hyperthyroidism usually is antithyroid medication or radioactive iodine therapy. If you have a lot of symptoms, your doctor may recommend you take antithyroid medication first to help you feel better. Then, you can decide whether to have radioactive iodine therapy.

• Antithyroid medications work best if you have mild hyperthyroidism, if this is the first time you are being treated for Graves' disease, if you are younger than 50, or if your thyroid gland is only swollen a little bit (small goiter).
• Radioactive iodine is often recommended if you have Graves' disease and are older than 50, or if you have thyroid nodules (toxic multinodular goiter) that are releasing too much thyroid hormone. Radioactive iodine is not used if:
  • You are younger than 20.
  • You are pregnant or you want to become pregnant within 6 months of treatment.
  • You are breast-feeding.
  • You have thyroiditis or another kind of hyperthyroidism that is often temporary.

Should I use antithyroid medication or radioactive iodine to treat my hyperthyroidism?

If you have symptoms such as a fast heartbeat, tremors, sweating, nervousness, or dry eyes, you may take some additional medications to treat those symptoms.

Surgery is not usually part of initial treatment. You may need surgery if your thyroid gland is so big that you have a hard time swallowing or breathing, or if a single large thyroid nodule is releasing too much thyroid hormone.

Ongoing treatment

During and after treatment for hyperthyroidism, you will have regular blood tests to check your levels of thyroid-stimulating hormone (TSH). You will also have regular thyroid hormone tests to check your levels of a hormone called T4. These tests are a good way to know how well your treatment is working. If your symptoms do not go away after your initial treatment, you may need to try a different treatment.

• If you have Graves' disease and have been taking antithyroid medication but your hyperthyroidism has not improved, you can continue to take antithyroid medication or you can try radioactive iodine therapy.
• If you have lots of side effects from antithyroid medications and radioactive iodine is not an option for you, you may need surgery to remove all or part of your thyroid gland (thyroidectomy).

Sometimes treatment cures your hyperthyroidism but may cause hypothyroidism. Hypothyroidism is the opposite of hyperthyroidism—instead of making too much thyroid hormone, your body is now making too little thyroid hormone. Hypothyroidism is most common after treatment with radioactive iodine. But it can also occur after surgery and sometimes after taking antithyroid medication.

It is important to call your doctor if you start to gain weight, feel tired, or feel cold more often than usual. These symptoms may mean you have hypothyroidism and you need to take a different medication called thyroid hormone medication. For more information, see the topic Hypothyroidism.

Treatment if the condition gets worse

If radioactive iodine or antithyroid medications are not working well, you may need:

• Another treatment of radioactive iodine.
• Surgery to remove all or part of your thyroid gland (thyroidectomy).

After treatment with radioactive iodine, you may develop hypothyroidism (too little thyroid hormone). Call your doctor if you have any of the symptoms of hypothyroidism such as gaining weight, feeling tired, or feeling cold more often than usual. If you do have hypothyroidism, you may need to take thyroid hormone medication for the rest of your life. For more information, see the topic Hypothyroidism.

Hyperthyroidism caused by Graves' disease is a genetic disease that you cannot prevent.

People who smoke are more likely to develop Graves' disease and Graves' ophthalmopathy than people who do not smoke.

It is important to see your doctor regularly so he or she can be sure that your hyperthyroidism treatment is working, that you are taking the right amount of medicine, and that you are not having any side effects.

If you are taking antithyroid medication, it is important to take the medicine at the same time every day.

If you have Graves' ophthalmopathy, you may need to use eyedrops to help moisten your eyes and wear sunglasses to protect your eyes.

To help reduce the symptoms of hyperthyroidism, you can:

• Lower stress. This helps relieve symptoms of anxiety and nervousness. For more information, see the topic Stress Management.
• Avoid caffeine. Caffeine can make symptoms worse, such as fast heartbeat, nervousness, and difficulty concentrating.
• Quit smoking. If you have Graves' disease and you are a smoker, you are more likely to develop Graves' ophthalmopathy. For more information, see the topic Quitting Smoking.

Antithyroid medication is often used for hyperthyroidism, because it works more quickly than radioactive iodine therapy. And unlike radioactive iodine therapy, which destroys part or all of the thyroid gland depending on the dosage used, medication does not cause permanent thyroid damage.

Sometimes, you may take antithyroid medication before you have radioactive iodine treatment or surgery—to bring your metabolism to normal, to make you feel better, or to reduce the chances of more serious problems.

Antithyroid medicine does control hyperthyroidism in many people, but the medicine does have some drawbacks.

• You have to take the medicine for at least 1 year.
• Your symptoms may come back after a few years, and then you have to start taking antithyroid medicine again or try a different treatment.
• There are some rare side effects from the medicine, ranging from a rash to a low white blood cell count, which can make it hard for your body to fight infection.

Sometimes your doctor will prescribe additional medicines to treat symptoms caused by hyperthyroidism, such as rapid heartbeat or dry eyes. These medicines can help you feel better while you wait for another treatment to begin to work.

Medication Choices

Antithyroid medications

Additional medications

What To Think About

• Antithyroid medicine may or may not make your hyperthyroidism permanently go away. Somewhere between 30% and 50% of people will have their hyperthyroidism go away (go into remission) after taking antithyroid medication for 1 or 2 years.¹
• Antithyroid medicine works best if you have mild hyperthyroidism, if this is the first time you are being treated for Graves' disease, if you are younger than 50, or if your thyroid gland is only swollen a little bit (small goiter). It is not used for thyroiditis.
• Antithyroid medicine is used instead of radioactive iodine if you are pregnant, breast-feeding, or trying to become pregnant.
• Children are treated with antithyroid medicine, because experts do not know if radioactive iodine treatment is safe for children. Treating children with antithyroid medicine is challenging, because it is hard to know how much medicine they need since they are growing so quickly.
• Your doctor may prescribe low doses of thyroid hormone medication to take with your antithyroid medicine so that your thyroid hormone levels do not get too low.

Should I use antithyroid medication or radioactive iodine to treat my hyperthyroidism?

Surgery for hyperthyroidism (thyroidectomy) removes part or all of the thyroid gland. Doctors rarely use this surgery to treat hyperthyroidism. You may need surgery if:

• Your thyroid gland is so big that it is hard for you to swallow or breathe.
• You have thyroid cancer or your doctor suspects you have thyroid cancer. For more information, see the topic Thyroid Cancer.
• You experienced serious side effects from taking antithyroid medications, and radioactive iodine is not an option for you.
• You have a large goiter that radioactive iodine treatment did not shrink.
• You have a single, large thyroid nodule that is making too much thyroid hormone, and radioactive iodine did not effectively treat the nodule.

Surgery Choices

The only surgery for hyperthyroidism is thyroidectomy.

What To Think About

If you are having surgery, your doctor will have you take antithyroid medications before surgery to bring your thyroid hormone levels as close to normal as possible.

After surgery, your doctor will check your thyroid hormone levels regularly, because you may develop hypothyroidism (too little thyroid hormone). Hypothyroidism is treated with thyroid hormone medication. For more information, see the topic Hypothyroidism.

Surgery is the fastest way to treat your hyperthyroidism, but it is not used very often and is more risky and expensive than other treatments.

Radioactive iodine is considered by many doctors in the United States to be the best treatment for hyperthyroidism. You swallow it in a liquid form, and it 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 does not harm any other parts of your body.

Other Treatment Choices

Radioactive iodine

What To Think About

Most people are cured of hyperthyroidism after one dose of radioactive iodine.

The main drawback of radioactive iodine is that it can damage your thyroid gland so that your body no longer produces enough thyroid hormone. This is a common result of treatment, and most people who receive radioactive iodine develop hypothyroidism (having too little thyroid hormone) within 1 to 10 years.¹ If you develop hypothyroidism, you will need to take thyroid hormone medication for the rest of your life. For more information, see the topic Hypothyroidism.

Radioactive iodine should not be used by children or by women who are pregnant, women who are breast-feeding, or women who want to become pregnant within 6 months of treatment.

Doctors have used radioactive iodine to treat hyperthyroidism for more than 60 years. There is no evidence that radioactive iodine causes cancer, infertility, or birth defects.

Should I use antithyroid medication or radioactive iodine to treat my hyperthyroidism?

Organization

Related Information

• Early Disease Detection
• Hypothyroidism
• Thyroid Nodules

Citations

1. Jameson JL, Weetman AP (2008). Hypothyroidism section of Disorders of the thyroid gland. In AS Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 2, pp. 2229–2233. New York: McGraw-Hill.

Other Works Consulted

• Ladenson PW (2005). Thyroid. In DC Dale, DD Federman, eds., ACP Medicine, section 3, chap. 1. New York: WebMD.

• Abramowicz M (2006). Treatment guidelines: Drugs for hypothyroidism and hyperthyroidism. Medical Letter on Drugs and Therapeutics, 4(44): 17–24.

• Cooper DS, et al. (2007). The thyroid gland. In DG Gardner, D Shoback, eds., Greenspan's Basic and Clinical Endocrinology, 8th ed., pp. 209–280. New York: McGraw-Hill.

• Dambro MR (2006). Hyperthyroidism. In Griffith's 5-Minute Clinical Consult, p. 550. Philadelphia: Lippincott Williams and Wilkins.

• Nygaard B (2007). Hyperthyroidism, search date April 2006. Online version of Clinical Evidence (4).

• Nygard B (2007). Hyperthyroidism, search date May 2007. Online version of BMJ Clinical Evidence. Also available online: http://www.clinicalevidence.com.

• U.S. Preventive Services Task Force (2004). Screening for thyroid disease: Recommendation statement. Annals of Internal Medicine, 140(2): 125–127.

• Yen PM (2007). Thyroid disorders. In LR Barker et al., eds., Principles of Ambulatory Medicine, 7th ed., pp. 1336–1366. Philadelphia: Lippincott Williams and Wilkins.