Hyperthyroidism is a condition in which the thyroid gland makes too much thyroid hormone. The condition is often called overactive thyroid.
The thyroid gland is an important organ of the endocrine system. It is located at the front of the neck just above where your collarbones meet. The gland makes the hormones that control the way every cell in the body uses energy. This process is called metabolism.
Many diseases and conditions can cause hyperthyroidism, including:
- Eating too much of foods that contain iodine
- Graves disease (most cases of hyperthyroidism)
- Inflammation (thyroiditis) of the thyroid due to viral infections, after pregnancy, or other causes
- Noncancerous growths of the thyroid gland or pituitary gland
- Some tumors of the testes or ovaries
- Taking large amounts of thyroid hormone
- Getting medical imaging tests with contrast dye that has iodine
Common symptoms include:
- Difficulty concentrating
- Frequent bowel movements
- Goiter (visibly enlarged thyroid gland) or thyroid nodules
- Hand tremor
- Heat intolerance
- Increased appetite
- Increased sweating
- Irregular menstrual periods in women
- Sleep problems
- Weight loss (or weight gain, in rare cases)
Other symptoms that can occur with this disease:
- Breast development in men
- Clammy skin
- Hair loss
- High blood pressure
- Itching - overall
- Lack of menstrual periods in women
- Nausea and vomiting
- Protruding eyes (exophthalmos)
- Rapid, forceful, or irregular heartbeat (palpitations)
- Skin blushing or flushing
Exams and Tests
The health care provider will do a physical exam. The exam may find the following:
- High systolic blood pressure (the first number in a blood pressure reading)
- Increased heart rate
- Enlarged thyroid gland
- Shaking of the hands
- Swelling or inflammation around the eyes
Blood tests are also ordered to measure your thyroid hormones TSH, T3, and T4.
You may also have blood tests to check:
Treatment depends on the cause and the severity of symptoms. Hyperthyroidism is usually treated with one or more of the following:
- Antithyroid medications
- Radioactive iodine to destroy the thyroid gland and stops the excess production of hormones
- Surgery to remove the thyroid
If your thyroid is removed with surgery or destroyed with radiation, you must take thyroid hormone replacement pills for the rest of your life.
Medicines called beta-blockers may be prescribed to treat symptoms such as fast heart rate, sweating, and anxiety until the hyperthyroidism can be controlled.
Hyperthyroidism is treatable. Some of its causes may go away without treatment.
Hyperthyroidism caused by Graves disease usually gets worse over time. It has many complications, some of which are severe and affect quality of life.
Thyroid crisis (storm), also called thyrotoxicosis, is a sudden worsening of hyperthyroidism symptoms that may occur with infection or stress. Fever, decreased alertness, and abdominal pain may occur. Patients need to be treated in the hospital.
Other complications of hyperthyroidism include:
- Heart problems such as fast heart rate, abnormal heart rhythm, heart failure
Surgery-related complications, including:
- Scarring of the neck
- Hoarseness due to nerve damage to the voice box
- Low calcium level due to damage to the parathyroid glands (located near the thyroid gland)
- Hypothyroidism (underactive thyroid)
When to Contact a Medical Professional
Call your health care provider if you have symptoms of hyperthyroidism. Go to an emergency room or call the local emergency number (such as 911), if you have:
- Change in consciousness
- Rapid, irregular heartbeat
Call your health care provider if you are being treated for hyperthyroidism and you develop symptoms of underactive thyroid, including:
- Mental and physical sluggishness
- Weight gain
Bahn RS, Burch HB, Cooper DS, et al. Hyperthyroidism and other causes of thyrotoxicosis: Management Guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists. Endocr Pract. 2011;17:457-520.
Mandel SJ, Larsen PR, Davies TF. Thyrotoxicosis. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Williams Textbook of Endocrinology. 12 ed. Philadelphia, Pa.: Elsevier Saunders; 2011: chap 12.
Last reviewed 6/7/2013 by Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.
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