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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. While your doctor is doing a test for another reason, he or she may discover that you have hyperthyroidism.
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.
Graves' disease causes most hyperthyroidism. In Graves' disease, the body's natural defence (immune) system attacks the thyroid gland. The thyroid reacts 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.
You may have no symptoms at all. Or:
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.
Your doctor will ask you about your symptoms and do a physical examination. 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.
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. Hyperthyroidism can lead to more serious problems. So even if your symptoms do not bother you, you still need treatment.
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.
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.
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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:
Uncommon causes of hyperthyroidism include tumours or eating foods or taking medicines that contain large amounts of iodine.
Hyperthyroidism can occur at any age but rarely affects children. It affects women more often than men.
You may have hyperthyroidism if you:
Also, 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.
People with Graves' disease often have additional symptoms, including:
Graves' ophthalmopathy is a possible complication of hyperthyroidism. It can occur 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:
In rare cases, hyperthyroidism can cause a life-threatening condition called thyroid storm, which happens when the thyroid gland releases large amounts of thyroid hormones in a short period of time.
If your thyroid gland makes too much thyroid hormone, you may 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 typically 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 occurs when the thyroid gland releases large amounts of thyroid hormones in a short period of time.
You are more likely to have hyperthyroidism if:
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 should also call your doctor if:
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.
Your family doctor or general practitioner can diagnose and treat hyperthyroidism. You may be referred to a specialist, such as the following:
Your doctor will ask questions about your medical history, do a physical examination, and order medical tests to diagnose hyperthyroidism.
If your doctor thinks you may have hyperthyroidism, he or she may order:
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:
If you have Graves' ophthalmopathy, your doctor may also do an ultrasound, an MRI, or a CT scan to look more closely at your eyes.
In Canada, screening is not recommended for people who do not have symptoms of thyroid problems. But testing is recommended for people who have vague symptoms that might be linked to thyroid dysfunction.footnote 1 More frequent testing may be recommended for people who have symptoms of hyperthyroidism or risk factors for the condition, such as:
There are three treatments for hyperthyroidism. Antithyroid medicine and radioactive iodine are the ones doctors use most often. In rare cases, surgery may be done. Hyperthyroidism can lead to more serious problems. So even if your symptoms are not bothering you, you still need treatment.
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. Discuss the benefits and risks of each kind of treatment with your doctor. For some people, more than one kind of treatment may be needed.
Initial treatment for hyperthyroidism usually is antithyroid medicine or radioactive iodine therapy. If you have a lot of symptoms, your doctor may recommend that you take antithyroid medicine first to help you feel better. Then you can decide whether to have radioactive iodine therapy.
If you have symptoms such as a fast heartbeat, tremors, sweating, nervousness, or dry eyes, you may take some additional medicines 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 you may need surgery if a single large thyroid nodule is releasing too much thyroid hormone.
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 hormones called T4 and T3. 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 repeat the treatment or try a different treatment.
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.
Be sure 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 medicine called thyroid hormone medicine. For more information, see the topic Hypothyroidism.
If radioactive iodine or antithyroid medicines are not working well, you may need:
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 medicine 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, also called thyroid eye disease, than people who do not smoke.
Be sure 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 medicine, take it 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:
Antithyroid medicine is often used for hyperthyroidism, because it works more quickly than radioactive iodine therapy. Radioactive iodine therapy destroys part or all of the thyroid gland, depending on the dosage used. But antithyroid medicine does not cause permanent thyroid damage.
You may take antithyroid medicine 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.
Your doctor may 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.
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:
If you are having surgery, your doctor will have you take antithyroid medicines 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 medicine. 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 than other treatments.
Radioactive iodine is considered by many doctors to be the best treatment for hyperthyroidism. You swallow it in a liquid form or capsule, and 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 does not harm any other parts of your body.
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 eventually develop hypothyroidism (having too little thyroid hormone). If you develop hypothyroidism, you will need to take thyroid hormone medicine 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 breastfeeding, 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.
CitationsBeaulieu M-D (1994). Screening for thyroid disorders and thyroid cancer in asymptomatic adults. In Canadian Task Force on the Periodic Health Examination, Canadian Guide to Clinical Preventive Health Care, pp. 611–618. Ottawa: Health Canada. Also available online: http://www.phac-aspc.gc.ca/publicat/clinic-clinique/pdf/s7c51e.pdf.Jameson JL, et al. (2015). Disorders of the thyroid gland. In DL Kasper et al., eds., Harrison's Principles of Internal Medicine, 19th ed., vol. 2, pp. 2283–2308. New York: McGraw-Hill Education.Other Works ConsultedBahn RS, et al. (2011). Hyperthyroidism and other causes of thyrotoxicosis: Management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists. Thyroid, 21(6): 593–646. Also available online: http://www.liebertonline.com/doi/full/10.1089/thy.2010.0417.Hueston WJ (2011). Hyperthyroidism. In ET Bope et al., eds., Conn's Current Therapy 2011, pp. 681–683. Philadelphia: Saunders.Mandel SJ, et al. (2011). Thyrotoxicosis. In S Melmed et al., eds., Williams Textbook of Endocrinology, 12th ed., pp. 362–405. Philadelphia: Saunders.Nygaard B (2014). Hyperthyroidism (primary). BMJ Clinical Evidence. http://clinicalevidence.bmj.com/x/systematic-review/0605/overview.html. Accessed April 14, 2016.
Current as of: March 31, 2020
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAnne C. Poinier MD - Internal MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family MedicineDavid C.W. Lau MD, PhD, FRCPC - Endocrinology
Current as of: March 31, 2020
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Anne C. Poinier MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & David C.W. Lau MD, PhD, FRCPC - Endocrinology
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