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Home , Hyperthyroidism, Thyroiditis, Thyroid disease

Hyperthyroidism

National Endocrine and Metabolic Diseases Information Service

What is ? Pituitary Hyperthyroidism is a disorder that occurs gland when the gland makes more thyroid hormone than the body needs. U.S. Department of Health and Hyperthyroidism is sometimes called Human Services thyrotoxicosis, the technical term for too much thyroid hormone in the blood. Thyroid NATIONAL hormones circulate throughout the body in INSTITUTES OF HEALTH the bloodstream and act on virtually every tissue and cell in the body. Hyperthyroidism TSH causes many of the body’s functions to speed up. About 1 percent of the U.S. population has hyperthyroidism.1 Thyroid What is the thyroid? The thyroid is a 2-inch-long, butterfly-shaped gland weighing less than 1 ounce. Located T -T in the front of the neck below the , 3 4 or voice box, it has two lobes, one on each side of the windpipe. The thyroid is one The thyroid’s production of —T3 of the glands that make up the endocrine and T4—is regulated by thyroid-stimulating hormone system. The glands of the (TSH), which is made by the . produce, store, and release hormones into the bloodstream. The hormones then travel through the body and direct the activity of heart and nervous system functions, body the body’s cells. temperature, muscle strength, skin dryness, menstrual cycles, weight, and The thyroid gland makes two thyroid levels. hormones, (T3) and thyroxine (T4). T3 is made from T4 and is Thyroid hormone production is regulated by the more active hormone, directly affecting thyroid-stimulating hormone (TSH), which the tissues. Thyroid hormones is made by the pituitary gland in the brain. metabolism, brain development, breathing, When thyroid hormone levels in the blood are low, the pituitary releases more TSH. When thyroid hormone levels are high, 1Golden SH, Robinson KA, Saldanha I, et al. the pituitary responds by decreasing TSH Prevalence and incidence of endocrine and metabolic disorders in the United States: a comprehensive production. review. Journal of Clinical Metabolism. 2009;94(6):1853–1878. What causes With Graves’ disease, the immune system makes an called thyroid stimulating hyperthyroidism? immunoglobulin (TSI) that attaches to Hyperthyroidism has several causes, thyroid cells. TSI mimics the action of TSH including and stimulates the thyroid to make too much • Graves’ disease thyroid hormone. • thyroid nodules More information about Graves’ disease is provided in the National Endocrine and • , or of the Metabolic Diseases Information Service thyroid (NEMDIS) fact sheet Graves’ Disease at • consuming too much www.endocrine.niddk.nih.gov. • overmedicating with synthetic thyroid Thyroid Nodules hormone, which is used to treat Thyroid nodules, also called adenomas, are underactive thyroid lumps in the thyroid. Thyroid nodules are Rarely, hyperthyroidism is caused by a common and usually noncancerous. About , which is a noncancerous 3 to 7 percent of the U.S. population has tumor of the pituitary gland. In this case, them.2 However, nodules may become hyperthyroidism is due to too much TSH. overactive and produce too much hormone. Graves’ Disease A single overactive nodule is called a toxic adenoma. Multiple overactive nodules are Graves’ disease, also known as toxic called toxic multinodular goiter. Often diffuse goiter, is the most common cause found in older adults, toxic multinodular of hyperthyroidism in the United States. goiter can produce a large amount of excess Graves’ disease is an autoimmune disorder. thyroid hormone. Normally, the immune system protects the body from by identifying and Thyroiditis destroying bacteria, viruses, and other potentially harmful foreign substances. But Thyroiditis is an inflammation of the thyroid in autoimmune diseases, the immune system that causes stored thyroid hormone to leak attacks the body’s own cells and organs. out of the thyroid gland. At first, the leakage raises hormone levels in the blood, leading to hyperthyroidism that lasts for 1 or 2 months. Most people then develop — when thyroid hormone levels are too low— before the thyroid is completely healed.

2Gharib H, Papini E, Paschke R, et al. American Association of Clinical Endocrinologists, Associazione Medici Endocrinologi, and European Thyroid Association medical guidelines for clinical practice for the diagnosis and management of thyroid nodules. Endocrine Practice. 2010;16(s1)1–43. 2 Hyperthyroidism Several types of thyroiditis can cause Overmedicating with Synthetic hyperthyroidism followed by hypothyroidism: Thyroid Hormone • . This condition Some people who take synthetic thyroid involves painful inflammation and hormone for hypothyroidism may take too enlargement of the thyroid. Experts much. People who take synthetic thyroid are not sure what causes subacute hormone should see their thyroiditis, but it may be related to provider at least once a year to have their a viral or bacterial infection. The thyroid hormone levels checked and follow condition usually goes away on its own the health care provider’s instructions about in a few months. the dosage. • . This type of Some other may also interact thyroiditis develops after a woman with synthetic thyroid hormone to raise gives birth. For more information, see hormone levels in the blood. People who the section titled “What happens with take synthetic thyroid hormone should ask and thyroid conditions?” their health care provider about interactions • Silent thyroiditis. This type of when starting new medications. thyroiditis is called “silent” because it is painless, as is postpartum What are the symptoms of thyroiditis, even though the thyroid may be enlarged. Like postpartum hyperthyroidism? thyroiditis, silent thyroiditis is probably Hyperthyroidism has many symptoms that an autoimmune condition and can vary from person to person. Some sometimes develops into permanent common symptoms of hyperthyroidism are hypothyroidism. • nervousness or irritability Consuming Too Much Iodine • or The thyroid uses iodine to make thyroid • heat intolerance hormone, so the amount of iodine consumed influences the amount of thyroid hormone • trouble sleeping the thyroid makes. In some people, • hand consuming large amounts of iodine may • rapid and irregular heartbeat cause the thyroid to make excess thyroid hormone. • frequent bowel movements or Sometimes significant amounts of iodine • are contained in medications—such as • mood swings , which is used to treat heart problems—or in supplements containing • goiter, which is an enlarged thyroid that seaweed. Some cough syrups also contain may cause the neck to look swollen and large amounts of iodine. See “Eating, Diet, can interfere with normal breathing and and Nutrition” for more information on swallowing iodine.

3 Hyperthyroidism Who is likely to develop Hyperthyroidism in the Aging hyperthyroidism? Population Women are two to 10 times more likely Hyperthyroidism is more common in people than men to develop hyperthyroidism.1 older than age 60 and is often caused by Certain factors can increase the chances of thyroid nodules. Older adults do not always developing thyroid disorders. People may display the more common symptoms of the need more regular testing if they disorder. For this reason hyperthyroidism in this age group is sometimes misdiagnosed as • have had a thyroid problem before, such or dementia—loss of intellectual as goiter or thyroid abilities, sometimes with emotional • have a family history of disturbance and personality changes. • have pernicious anemia, a B12 For example, older adults with deficiency; type 1 ; or primary hyperthyroidism may seem disinterested , a hormonal or withdraw socially. Older adults with disorder hyperthyroidism may lose their appetites, whereas younger people with the condition • eat large amounts of food containing tend to have increased appetites. Older iodine, such as kelp, or use iodine- adults may also have different physical containing medications such as symptoms and may be more at risk from amiodarone, a heart subclinical hyperthyroidism than younger • are older than age 60 patients. • were pregnant or delivered a baby For people older than age 60, subclinical within the past 6 months hyperthyroidism increases their chance of Getting tested routinely helps uncover developing a rapid, irregular heartbeat, thyroid problems—especially subclinical a condition known as , problems. Subclinical means a person has which may lead to or stroke. no apparent symptoms. Some health care Untreated hyperthyroidism can also speed providers treat subclinical hyperthyroidism the bone-thinning disease , immediately. Others prefer to leave it particularly in women, and increase the untreated but monitor their patients for signs likelihood of bone fractures. that the condition is worsening.

4 Hyperthyroidism What happens with Postpartum thyroiditis. This inflammation of the thyroid gland affects about 4 to pregnancy and thyroid 10 percent of women in the first year conditions? after giving birth.4 Postpartum thyroiditis Hyperthyroidism. During pregnancy, causes hyperthyroidism that usually lasts hyperthyroidism is usually caused by for 1 to 2 months and is believed to be an Graves’ disease and occurs in about one autoimmune condition. of every 500 .3 Uncontrolled Women with postpartum thyroiditis often hyperthyroidism raises the chance of develop hypothyroidism before the thyroid , preterm delivery, and gland is completely healed. The condition is preeclampsia—a dangerous rise in blood likely to recur with future pregnancies. pressure in late pregnancy. Postpartum thyroiditis sometimes goes Hyperthyroidism in a newborn can result undiagnosed because the symptoms are in rapid heart rate, which can lead to heart mistaken for postpartum blues—the failure; early closure of the soft spot in the exhaustion and moodiness that sometimes skull; poor ; irritability; and follow delivery. If symptoms of fatigue sometimes an enlarged thyroid that can and lethargy do not go away within a few press against the windpipe and interfere with months or a woman develops postpartum breathing. depression, she should talk with her health Women with Graves’ disease and their care provider. She may have developed a newborns should be closely monitored permanent thyroid condition and will need to by their health care team. Women with take medication. hyperthyroidism should discuss their More information about pregnancy and condition with their health care provider thyroid disease is provided in the NEMDIS before becoming pregnant. fact sheet Pregnancy and Thyroid Disease at Symptoms of hyperthyroidism may be www.endocrine.niddk.nih.gov. difficult to assess during pregnancy. Normally, the thyroid gland gets bigger in healthy women when they become pregnant. That normal enlargement, combined with fatigue, makes a new thyroid problem easy to miss. A rapid and irregular heartbeat, a slight , and unexplained weight loss or failure to have normal pregnancy weight gain are signs that hyperthyroidism could be developing.

4Ogunyemi DA. Autoimmune thyroid 3Komal PS, Mestman JH. Graves hyperthyroidism disease and pregnancy. emedicine website. and pregnancy: a clinical update. Endocrine Practice. http://emedicine.medscape.com/article/261913-overview. 2010;16(1):118–129. Updated March 12, 2012. Accessed April 10, 2012. 5 Hyperthyroidism How is hyperthyroidism Radioactive iodine uptake test. The radioactive iodine uptake test measures the diagnosed? amount of iodine the thyroid collects from Many symptoms of hyperthyroidism are the bloodstream. Measuring the amount of the same as those of other diseases, so iodine in a person’s thyroid helps the health hyperthyroidism usually cannot be diagnosed care provider determine what is causing a based on symptoms alone. With suspected person’s hyperthyroidism. For example, low hyperthyroidism, health care providers take levels of iodine uptake might be a sign of a medical history and perform a thorough thyroiditis, whereas high levels could indicate physical exam. Health care providers Graves’ disease. may then use several blood tests, such as the following, to confirm a diagnosis of Thyroid scan. A thyroid scan shows how hyperthyroidism and find its cause: and where iodine is distributed in the thyroid. The images of nodules and other TSH test. The ultrasensitive TSH test is possible irregularities help the health care usually the first test a health care provider provider diagnose the cause of a person’s performs. This test detects even tiny hyperthyroidism. amounts of TSH in the blood and is the most accurate measure of thyroid activity More information about testing for thyroid available. The TSH test is especially problems is provided in the NEMDIS useful in detecting mild hyperthyroidism. fact sheet at Generally, a TSH reading below normal www.endocrine.niddk.nih.gov. means a person has hyperthyroidism and a reading above normal means a person has How is hyperthyroidism hypothyroidism. treated? Health care providers may conduct Health care providers treat hyperthyroidism additional tests to help confirm the diagnosis with medications, radioiodine therapy, or determine the cause of hyperthyroidism. or thyroid surgery. The aim of treatment T and T test. This test shows the is to bring thyroid hormone levels to a 3 4 normal state, thus preventing long-term levels of T3 and T4 in the blood. With hyperthyroidism, the levels of one or both of complications, and to relieve uncomfortable these hormones in the blood are higher than symptoms. No single treatment works for normal. everyone. Thyroid-stimulating immunoglobulin Treatment depends on the cause of (TSI) test. This test, also called a thyroid- hyperthyroidism and how severe it is. When stimulating antibody test, measures the choosing a treatment, health care providers level of TSI in the blood. Most people with consider a patient’s age, possible allergies Graves’ disease have this antibody, but to or side effects of the medications, people whose hyperthyroidism is caused by other conditions such as pregnancy or other conditions do not. heart disease, and the availability of an experienced thyroid surgeon.

6 Hyperthyroidism Finding the right specialist for treatment is an important first step. Some Stop your antithyroid medication and professional societies, listed under “For call your health care provider right away More Information,” and endocrinology if you develop any of the following while departments in local teaching hospitals can taking antithyroid medications: provide the names of local specialists. • fatigue Medications • weakness Beta blockers. Health care providers • vague abdominal pain may prescribe a medication called a to reduce symptoms until other • loss of appetite treatments take effect. Beta blockers act • skin rash or itching quickly to relieve many of the symptoms of hyperthyroidism, such as tremors, rapid • easy bruising heartbeat, and nervousness, but do not stop • yellowing of the skin or whites of thyroid hormone production. Most people the eyes, called feel better within hours of taking these medications. • persistent sore throat Antithyroid medications. Antithyroid • fever therapy is the easiest way to treat hyperthyroidism. Antithyroid medications interfere with thyroid hormone production but don’t usually have permanent results. In the United States, health care providers Antithyroid medications are not used to treat prescribe the antithyroid medication thyroiditis. methimazole (Tapazole, Northyx) for most types of hyperthyroidism. Once treatment with antithyroid medications begins, thyroid hormone levels may not Antithyroid medications and pregnancy. move into the normal range for several Because pregnant and breastfeeding women weeks or months. The average treatment cannot receive radioiodine therapy, they time is about 1 to 2 years, but treatment can are usually treated with an antithyroid continue for many years. medication instead. However, experts agree that women in their first trimester Antithyroid medications can cause side of pregnancy should not take methimazole effects in some people, including due to the rare occurrence of damage to the fetus. Another antithyroid medication, • allergic reactions such as rashes and (PTU), is available for itching women in this stage of pregnancy or for • a decrease in the number of white women who are allergic to or intolerant of blood cells in the body, which can lower methimazole and have no other treatment resistance to infection options. • liver failure, in rare cases

7 Hyperthyroidism Health care providers may prescribe PTU More than one round of radioiodine therapy for the first trimester of pregnancy and may be needed to bring thyroid hormone switch to methimazole for the second and production into the normal range. In the third trimesters. Some women are able meantime, treatment with beta blockers can to stop taking antithyroid medications control symptoms. in the last 4 to 8 weeks of pregnancy due Almost everyone who receives radioactive to the remission of hyperthyroidism that iodine treatment eventually develops occurs during pregnancy. However these hypothyroidism. But health care providers women should continue to be monitored for consider this an acceptable outcome recurrence of thyroid problems following because hypothyroidism is easier to treat delivery. and has fewer long-term complications Studies have shown that mothers taking than hyperthyroidism. People who develop antithyroid medications may safely hypothyroidism must take synthetic thyroid breastfeed. However, they should take only hormone. moderate doses, less than 10−20 milligrams Radioiodine and pregnancy. Although daily, of the antithyroid medication iodine-131 is not known to cause birth methimazole. Doses should be divided and defects or infertility, radioiodine therapy is taken after feedings, and the infants should not used in pregnant women or women who be monitored for side effects.4 are breastfeeding. Radioactive iodine can Women requiring higher doses of be harmful to the fetus’ thyroid and can be the antithyroid medication to control passed from mother to child in milk. hyperthyroidism should not breastfeed. Experts recommend that women wait a year after treatment before becoming pregnant. Radioiodine Therapy Radioactive iodine-131 is a common and Thyroid Surgery effective treatment for hyperthyroidism. In The least-used treatment is surgery to radioiodine therapy, patients take radioactive remove part or most of the thyroid gland. iodine-131 by mouth. Because the thyroid Sometimes surgery may be used to treat gland collects iodine to make thyroid • pregnant women who cannot tolerate hormone, it will collect the radioactive iodine antithyroid medications from the bloodstream in the same way. The radioactive iodine gradually destroys the cells • people with large goiters that make up the thyroid gland but does not • people who have cancerous thyroid affect other body tissues. nodules, though hyperthyroidism does not cause cancer

8 Hyperthyroidism Before surgery, the health care provider Eating, Diet, and Nutrition may prescribe antithyroid medications Experts recommend that people eat a to temporarily bring a patient’s thyroid balanced diet to obtain most nutrients. hormone levels into the normal range. This More information about diet and nutrition presurgical treatment prevents a condition is provided by the National Agricultural called —a sudden, severe Library at www.nutrition.gov. worsening of symptoms—that can occur when hyperthyroid patients have general Dietary Supplements anesthesia. Iodine is an essential for the thyroid. When part of the thyroid is removed—as a However, people with autoimmune thyroid treatment for toxic nodules, for example— disease may be sensitive to harmful side thyroid hormone levels may return to effects from iodine. Taking iodine drops or normal. But some surgical patients may eating foods containing large amounts of still develop hypothyroidism and need to iodine—such as seaweed, dulse, or kelp— take synthetic thyroxine, a medication that may cause or worsen hyperthyroidism. is identical to the hormone, T4, made by the More information about iodine is provided thyroid. If the entire thyroid is removed, by the National Library of Medicine in lifelong thyroid hormone medication is the fact sheet, Iodine in diet, available at necessary. After surgery, health care www.nlm.nih.gov/medlineplus. providers will continue to monitor patients’ Women need more iodine when they are thyroid hormone levels. pregnant—about 250 micrograms a day— Although uncommon, certain problems can because the baby gets iodine from the occur in thyroid surgery. The parathyroid mother’s diet. In the United States, about glands can be damaged because they are 7 percent of pregnant women may not located very close to the thyroid. These get enough iodine in their diet or through glands help control calcium and phosphorus prenatal vitamins.6 Choosing iodized salt— levels in the body. Damage to the laryngeal salt supplemented with iodine—over plain nerve, also located close to the thyroid, salt and prenatal vitamins containing iodine can lead to voice changes or breathing will ensure this need is met. problems. But when surgery is performed by To help ensure coordinated and safe care, an experienced surgeon, less than 1 percent people should discuss their use of dietary of patients have permanent complications.5 supplements, such as iodine, with their People who need help finding a surgeon can health care provider. Tips for talking with contact one of the organizations listed under health care providers are available from “For More Information.” the National Center for Complementary and Alternative Medicine’s Time to Talk campaign at www.nccam.nih.gov.

5Yeung SJ, Habra MA, Chiu AC. Graves disease. 6Zimmerman MB. in pregnancy emedicine website. http://emedicine.medscape.com/ and the effects of maternal iodine supplementation on article/120619-overview. Updated September 30, 2011. the offspring: a review. American Journal of Clinical Accessed April 10, 2012. Nutrition. 2009;89(2):668S–672S. 9 Hyperthyroidism Hope through Research Points to Remember The National Institute of Diabetes and • Hyperthyroidism is a disorder that Digestive and Kidney Diseases (NIDDK) occurs when the thyroid gland conducts and supports research into many makes more thyroid hormone than kinds of disorders, including Graves’ the body needs. disease. Researchers throughout the United States and the world are working to better

• Hyperthyroidism is most often understand, prevent, and treat this disease. caused by Graves’ disease, an autoimmune disorder. Other causes National Institutes of Health (NIH)- include thyroid nodules, thyroiditis, supported scientists are investigating the consuming too much iodine, and development, , and overmedicating with synthetic genetics of thyroid function disorders thyroid hormone. to further understand thyroid diseases. Scientists continue to study treatment • Some symptoms of hyperthyroidism options for hyperthyroidism and other are nervousness or irritability, thyroid disorders. fatigue or muscle weakness, heat intolerance, trouble sleeping, The following federally funded research hand tremors, rapid and irregular studies and clinical trials are currently under heartbeat, frequent bowel way: movements or diarrhea, weight loss,

mood swings, and goiter. • Evaluation of Patients With Thyroid Disorders, funded under NIH clinical • Hyperthyroidism is much more trial number NCT00001159 common in women than men. • Trial of Rituximab for Graves’ • Hyperthyroidism is also more Ophthalmopathy, funded under NIH common in people older than age clinical trial number NCT00595335 60 and is often caused by thyroid

nodules. Hyperthyroidism in • Phase II Randomized Controlled Study this age group is sometimes of Sequential Orbital Radiotherapy for misdiagnosed as depression or Graves’ Ophthalmopathy, funded under dementia. For people older than NIH clinical trial number NCT00004660 age 60, subclinical hyperthyroidism Participants in clinical trials can play a more increases their chance of developing active role in their own health care, gain atrial fibrillation. access to new research treatments before • Women with hyperthyroidism they are widely available, and help others should discuss their condition with by contributing to medical research. For their health care provider before information about current studies, visit becoming pregnant. www.ClinicalTrials.gov. • Hyperthyroidism is treated with medications, radioiodine therapy, or thyroid surgery. No single treatment works for everyone.

10 Hyperthyroidism For More Information The Hormone Foundation 8401 Connecticut Avenue, Suite 900 American Academy of Otolaryngology— Chevy Chase, MD 20815–5817 Head and Neck Surgery Phone: 1–800–HORMONE 1650 Diagonal Road (1–800–467–6663) Alexandria, VA 22314–2857 Fax: 301–941–0259 Phone: 703–836–4444 Email: [email protected] Internet: www.entnet.org Internet: www.hormone.org American Association of Clinical Endocrinologists Acknowledgments 245 Riverside Avenue, Suite 200 Jacksonville, FL 32202 Publications produced by the NIDDK are Phone: 904–353–7878 carefully reviewed by both NIDDK scientists Fax: 904–353–8185 and outside experts. This publication was Internet: www.aace.com originally reviewed by Lewis Braverman, M.D., Boston University School of Medicine American Thyroid Association and Boston Medical Center; Leonard 6066 Leesburg Pike, Suite 550 Wartofsky, M.D., M.A.C.P., Washington Falls Church, VA 22041 Hospital Center; Nicholas J. Sarlis, M.D., Phone: 1–800–THYROID NIDDK; Nabeel Babar, M.D., NIDDK; and (1–800–849–7643) or 703–998–8890 the National Eye Institute, NIH. Fax: 703–998–8893 Email: [email protected] Internet: www.thyroid.org You may also find additional information about this topic by visiting MedlinePlus at www..gov. The Endocrine Society This publication may contain information about 8401 Connecticut Avenue, Suite 900 medications. When prepared, this publication Chevy Chase, MD 20815 included the most current information available. For updates or for questions about any medications, Phone: 1–888–363–6274 or 301–941–0200 contact the U.S. Food and Drug Administration toll- Fax: 301–941–0259 free at 1–888–INFO–FDA (1–888–463–6332) or visit Email: [email protected] www.fda.gov. Consult your health care provider for more information. Internet: www.endo-society.org Graves’ Disease and Thyroid Foundation P.O. Box 2793 The U.S. Government does not endorse or favor any Rancho Santa Fe, CA 92067 specific commercial product or company. Trade, Phone: 1–877–643–3123 proprietary, or company names appearing in this Fax: 1–877–643–3123 document are used only because they are considered necessary in the context of the information provided. Email: [email protected] If a product is not mentioned, the omission does not Internet: www.gdatf.org mean or imply that the product is unsatisfactory.

11 Hyperthyroidism The National Endocrine and Metabolic Diseases Information Service 6 Information Way Bethesda, MD 20892–3569 Phone: 1–888–828–0904 TTY: 1–866–569–1162 Fax: 703–738–4929 Email: [email protected] Internet: www.endocrine.niddk.nih.gov The National Endocrine and Metabolic Diseases Information Service is an information dissemination service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health, which is part of the U.S. Department of Health and Human Services. The NIDDK conducts and supports biomedical research. As a public service, the NIDDK has established information services to increase knowledge and understanding about health and disease among patients, health professionals, and the public.

This publication is not copyrighted. The NIDDK encourages users of this publication to duplicate and distribute as many copies as desired. This publication is available at www.endocrine.niddk.nih.gov.

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES National Institutes of Health

NIH Publication No. 12–5415 July 2012

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