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What is hyperthyroidism?

Hyperthyroidism means your thyroid gland is too active. This tiny gland is found in your neck. An overactive thyroid gland makes too much thyroid hormone. This makes your metabolism work at a faster rate.

What causes hyperthyroidism?

Hyperthyroidism has several causes. These include:

  • Graves' disease. This is an autoimmune disorder. It is themost common cause of hyperthyroidism. It happens when an antibody overstimulates the thyroid. This condition is most often found in young to middle-aged women. It also tends to run in families.
  • Toxic nodular goiter. This condition happens when 1 or more nodules of the thyroid gland become too active. Doctors do not know what causes this to happen.
  • Thyroiditis. It occurs when the thyroid becomes irritated. It temporarily causes the thyroid to be overactive. The thyroid then often becomes underactive.

Hyperthyroidism may occur for other reasons. These include:

  • Taking too much thyroid hormone medicine to treat an underactive thyroid
  • Having too much iodine in your diet
  • Having a benign tumor in the pituitary gland

Who is at risk for hyperthyroidism?

These things may make it more likely for you to get hyperthyroidism:

  • Sex. Women are more likely than men to develop it.
  • Age. Most people with the condition are older than 60.
  • Thyroid problems in the past
  • Family history of thyroid problems
  • Certain conditions, such as type 1 diabetes
  • Too much iodine. This can happen if you eat a lot of foods or take too much medicine that contains this chemical.
  • Pregnancy. Women who are pregnant or who have delivered a baby within the previous 6 months are more likely to get it.

What are the symptoms of hyperthyroidism?

Symptoms and signs are different for each person. Here are the most common ones:

  • Nervousness
  • Irritability
  • Sweating more than normal
  • Thinning of the skin
  • Fine, brittle hair
  • Weak muscles, especially in the upper arms and thighs
  • Shaky hands
  • Fast heartbeat (palpitations)
  • High blood pressure
  • More bowel movements than normal
  • Weight loss
  • Problems sleeping
  • Prominent eyes
  • Sensitivity to bright light
  • Confusion
  • Irregular menstrual cycle in women
  • Tiredness (fatigue)
  • Thyroid gland is larger than normal (goiter)

These symptoms may look like other health problems. Always see your health care provider for a diagnosis.

How is hyperthyroidism diagnosed?

Your health care provider will ask about your past health. You will also need an exam. Other tests that can help diagnose hyperthyroidism include:

  • Blood tests. They can measure the amount of thyroid hormone and thyroid stimulating hormone in the blood.
  • Thyroid ultrasound. This test can see if your thyroid gland has any nodules. 
  • Thyroid scan. This test uses a radioactive substance to make an image of the thyroid.

How is hyperthyroidism treated?

The goal of treatment is to have your thyroid gland work as it should. The gland will then make normal levels of thyroid hormone. Your health care provider will figure out the best treatment for you based on:

  • How old you are
  • Your overall health and past health
  • How sick you are
  • How well you can handle specific medicines, procedures, or therapies
  • Your type of hyperthyroidism
  • Your opinion or preference

Treatment may include:

  • Medicine. It can help lower the level of thyroid hormones in the blood.
  • Radioactive iodine. It comes in the form of a pill or liquid. It can help slow down how much thyroid hormones are made.
  • Surgery. You may need to have all or part of your thyroid removed.
  • Beta-blocking agents. These drugs block the action of the thyroid hormone on the body. That helps with rapid heart rate and palpitations.

What are the complications of hyperthyroidism?

If your hyperthyroidism is not treated, these complications may happen:

  • Thyroid crisis, when symptoms get worse because of stress or illness
  • Heart problems, such as an abnormal rhythm or heart failure
  • Osteoporosis
  • Pregnancy problems, such as the loss of a fetus, early delivery, and preeclampsia or high blood pressure

When should I call my health care provider?

Tell your health care provider if your symptoms get worse or you have new symptoms. If you are a woman of childbearing age who wants to become pregnant, talk with your health care provider first.

Key points about hyperthyroidism

  • Hyperthyroidism means your thyroid gland is too active. This tiny gland is found in your neck. If it is overactive, it makes too much thyroid hormone. As a result, your body’s metabolism begins to work at a faster rate.
  • This condition can be caused by Graves' disease, toxic nodular goiter, thyroiditis, and taking too much thyroid medicine.
  • Symptoms may include nervousness, irritability, extra sweating (perspiration), and fine, brittle hair.
  • Treatment may include medicine, radioactive iodine, surgery, or beta-blocking medicine.

Next steps

Tips to help you get the most from a visit to your health care provider:
  • Before your visit, write down questions you want answered.
  • Bring someone with you to help you ask questions and remember what your provider tells you.
  • At the visit, write down the names of new medicines, treatments, or tests, and any new instructions your provider gives you.
  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your provider if you have questions.
Online Medical Reviewer: Hanrahan, John, MD
Online Medical Reviewer: newMentor board-certified, academically affiliated clinician
Date Last Reviewed: 2/24/2014
© 2000-2015 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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