What is hyperthyroidism?

Hyperthyroidism means your thyroid gland is too active. This tiny butterfly type of 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 may include:

• Graves disease. It is the most common cause of hyperthyroidism. This is an autoimmune disorder. 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 one or more lumps (nodules) of the thyroid gland make thyroid hormone independently from the normal feedback mechanism. Health experts don't know what causes this to happen. In most cases, the nodules are not cancer (benign). But in rare cases, the overactive thyroid tissue is cancer.

• Thyroiditis. This occurs when the thyroid becomes irritated. It temporarily causes the thyroid to release large amounts of thyroid hormone. The thyroid then often becomes underactive until it recovers. Viruses are often the cause of thyroiditis.

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 or in medicines (very rare)

• Having a noncancerous tumor in the pituitary gland that makes your thyroid overactive

Who is at risk for hyperthyroidism?

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

• You are a woman.

• You are older than age 40.

• You have had thyroid problems in the past.

• Your family has a history of thyroid problems.

• You have certain conditions, such as type 1 diabetes.

• You consume too much iodine. This can happen if you eat a lot of iodine-rich foods or take too much medicine that has this chemical.

• You are pregnant or have had a baby in the last 6 months.

What are the symptoms of hyperthyroidism?

Symptoms 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, diarrhea

• Weight loss

• Trouble dealing with the heat

• Problems sleeping

• Prominent eyes

• Sensitivity to bright light

• Confusion

• Irregular menstrual cycle in women

• Tiredness and lack of energy (fatigue)

• Larger than normal thyroid gland (goiter)

• Pain in the lower neck in the thyroid gland (with thyroiditis)

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

How is hyperthyroidism diagnosed?

Your healthcare provider will ask about your health history. You will also need a physical exam. Other tests that can help diagnose hyperthyroidism include:

• Blood tests. They can measure the amount of thyroid hormone and thyroid stimulating hormone in your 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?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

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 slowly destroys the cells of the thyroid gland so that less thyroid hormone is made.

• Surgery. You may need to have all or part of your thyroid removed.

• Beta blockers. These medicines block the action of the thyroid hormone on the body. That helps with rapid heart rate and palpitations.

• Steroids. These can be used to quiet the inflammation causing some forms of thyroiditis (in some cases)

What are possible 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

• Weak, brittle bones (osteoporosis)

• Pregnancy problems, such as miscarriage, early delivery, and preeclampsia or high blood pressure

When should I call my healthcare provider?

Tell your healthcare provider if your symptoms get worse or you have new symptoms. If you are a woman of childbearing age with one of these thyroid conditions and want to become pregnant, talk with your provider first.

Key points about hyperthyroidism

• Hyperthyroidism means you have too much thyroid hormone in your bloodstream. This tiny gland is found in your neck. If it is overactive, it makes too much thyroid hormone. Your body’s metabolism then 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 healthcare provider:

• Know the reason for your visit and what you want to happen.

• 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 name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new directions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions, especially after office hours and on weekends.