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.
Too much thyroid hormone can also affect your heart, muscles, bones, and cholesterol.
Hyperthyroidism can occur at any age but rarely affects children. It affects women more often than men.
Your thyroid is a gland in the front of your neck.
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.
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.
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.
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.
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Graves' disease is the most common cause of hyperthyroidism. In Graves' disease, the body's natural defense (immune) system attacks the thyroid gland. This causes the thyroid to make too much thyroid hormone. Graves' disease often runs in families.
Other common causes include:
These are abnormal growths in the thyroid gland. They cause the thyroid gland to make too much thyroid hormone.
This condition 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 no symptoms of hyperthyroidism. Or:
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 depend on how much hormone your thyroid gland is making, how long you have had the condition, and your age.
Graves' ophthalmopathy, also called thyroid eye disease, can be a problem caused by hyperthyroidism. It can occur before, after, or at the same time as symptoms of hyperthyroidism.
Thyroid eye disease can include eyes that bulge, are red, and are sensitive to light, and blurring or double vision. People who smoke are more likely to have these problems.
Thyroid eye disease may get worse for a time if you have radioactive iodine treatment. But the condition may get better if you take antithyroid medicine.
In rare cases, hyperthyroidism can cause a condition called thyroid storm, which can cause death. This happens when the thyroid gland releases large amounts of thyroid hormones in a short period of time.
Without treatment, hyperthyroidism can lead to:
The most serious problem linked to hyperthyroidism is a life-threatening condition called thyroid storm.
Call your doctor now if you have been diagnosed with hyperthyroidism and:
You should also call your doctor if:
Watchful waiting is a wait-and-see approach. 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. Early treatment may reduce your chances of having more serious problems.
To diagnose hyperthyroidism, your doctor will ask questions about your past health and your symptoms and will do a physical exam.
If your doctor thinks you may have hyperthyroidism, he or she may order:
When you are being treated for this condition, your doctor will test your TSH and thyroid hormones several times a year to see how well your treatment is working.
Your doctor may also do tests that can help find the cause of your condition. These can include an antithyroid antibody test, a thyroid scan, and a radioactive iodine uptake test.
If your hyperthyroidism 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.
Treatment for hyperthyroidism usually starts with these treatments:
If you have Graves' disease and have been taking antithyroid medicine but your hyperthyroidism has not improved, you can continue to take antithyroid medicine or you can try radioactive iodine therapy.
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. Some people need more than one kind of treatment.
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. So even if your symptoms are not bothering you, you still need treatment.
You may need surgery if:
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 medicine. If you do have hypothyroidism, you may need to take thyroid hormone medicine for the rest of your life.
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 may take beta-blockers or other medicines to treat symptoms such as a fast heartbeat or dry eyes until your thyroid improves.
Antithyroid medicine works best if:
The medicine is used instead of radioactive iodine if you are pregnant, breastfeeding, or trying to become pregnant.
Children are treated with antithyroid medicine. That's because experts don't know if radioactive iodine treatment is safe for children.
The medicine works much better in people who have mild disease. Up to 30 out of 100 people in the United States will have their hyperthyroidism go away after they take the medicine for 12 to 18 months.footnote 1
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 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).
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:
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