What Is Hyperthyroidism?

The butterfly-shaped thyroid gland is located in the neck and makes hormones that help regulate metabolism. Overactive thyroid, or hyperthyroidism, is a type of thyroid disease that occurs when the thyroid gland produces high levels of thyroid hormones. Triiodothyronine (T3) and thyroxine (T4) are hormones the thyroid gland produces.

Healthcare provider checking a pulse

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Hypothyroidism vs. Hyperthyroidism

The prefix "hyper" means "excessive" or "too much." Conversely, "hypo" means "less than normal" or "too little." Regarding conditions of the thyroid, hyperthyroidism is when the thyroid gland makes too much thyroid hormone, and hypothyroidism is when it makes too little.

Since thyroid hormones help to regulate metabolism, hyperthyroidism speeds up metabolism while hypothyroidism slows down metabolism. Other parts of the body are also affected.

Thyroid Gland and Bodily Impact

The thyroid gland impacts almost every organ in the body and various bodily functions, including:

  • Breathing
  • Heart rate
  • Weight
  • Digestion
  • Mood
  • Menstrual cycles
  • Fertility

Hyperthyroidism Symptoms

Hyperthyroidism causes an overactive thyroid gland, which releases hormones that speed up bodily processes. People with this condition tend to feel more hungry yet lose weight even if they eat more. Additionally, they may experience symptoms related to accerated body processes. These symptoms may include the following:

Hyperthyroidism Symptoms in Women

Thyroid disease such as hyperthyroidism is up to 8 times more common among people assigned female at birth than those assigned male. The risk may increase for people around the time of menopause. People with female reproductive organs and hyperthyroidism may experience menstrual changes, such as light and infrequent periods.

The thyroid hormone can affect fertility in women and men through various mechanisms. There is limited research on the impact of hyperthyroidism and fertility; however, researchers suggest that treatments to restore normal thyroid function can reverse fertility issues related to thyroid disease.

What Causes Hyperthyroidism?

The most common cause of hyperthyroidism is a condition called Graves' disease. Infections and medications can lead to thyroid gland inflammation, which can cause hyperthyroidism.

Some people with an underactive thyroid (hypothyroidism) take medications to increase thyroid hormone levels, which can cause hyperthyroidism. This can mean fluctuating between hyperthyroidism and hypothyroidism while medications are balanced. There are also some less common possibilities, including tumors on the thyroid gland, testes, or ovaries.

Risk Factors for Hyperthyroidism

Women, especially those over age 60, are at an increased risk for developing hyperthyroidism. Others who may be at increased risk include those with the following:

  • Personal or family history of thyroid problems
  • A history of thyroid surgery or treatment
  • Gave birth or were pregnant in the last six months

People with the following diagnoses may also be at increased risk:

Hyperthyroidism Diagnosis: What Tests Are Used?

Diagnosing hyperthyroidism requires an office visit with a healthcare professional. They may assess your condition based on your medical history, a physical exam, and other diagnostic tests. An ultrasound is occasionally done to check for possible nodules or tumors.

The three main tests used to diagnose hyperthyroidism are:

  • Blood tests: A provider will check for elevated T3 and thyroxine T4 levels, which indicate hyperthyroidism.
  • Iodine uptake scan: This test involves taking a dose of iodine and then waiting a few hours before measuring how much iodine is in the thyroid.
  • Thyroid scan: This test involves taking images of the thyroid gland to detect or rule out any abnormalities in the thyroid's shape or to diagnose hyperthyroidism.

Hyperthyroidism Treatment

Hyperthyroidism treatment depends on each person and their preferences, the cause of the overactive thyroid, and the condition's severity. For example, hyperthyroidism caused by Graves' disease is typically treated by taking a capsule or liquid medication called radioiodine therapy.

The three primary treatment options for hyperthyroidism are:

  • Medications: Beta-blockers are used to decrease the symptoms of hyperthyroidism, while thionamides can reduce the amount of thyroid hormone the body makes.
  • Radioactive iodine: This treatment option works by attacking thyroid cells so the thyroid can no longer make as much thyroid hormone.
  • Surgical options: You may require surgery to remove tumors from the thyroid gland, part of the thyroid gland, or the entire thyroid gland.

Is Untreated Hyperthyroidism Dangerous?

It is essential to seek care for hyperthyroidism. Leaving this condition untreated could lead to severe and life-threatening complications. Dangerous complications of hyperthyroidism may be called thyroid storms or thyroid crises.

Some signs of serious hyperthyroid complications include:

Does Treatment Reverse Hyperthyroidism?

Hyperthyroidism can be reversed with treatment; however, this condition often needs to be treated with medication for life. For example, radioactive iodine treatments prevent the thyroid from making too much thyroid hormone. It works so well that it leads to the thyroid not producing enough thyroid hormone, so you may need medication to treat an underactive thyroid.

How Long Do You Need Hyperthyroidism Treatment?

The duration of hyperthyroidism treatment depends on your condition and your treatment approach. You may need to take some medications for a few months and others for life.

When your thyroid is surgically removed, you need medications to replace the hormones no longer made by the body. Some people, however, may not need to continue treatment or medication. If only one dose of radioactive iodine is given, hyperthyroidism is less likely to occur, and long-term medications may not be needed.

How Important Is Diet With Hyperthyroidism?

Diet does affect hyperthyroidism and treatment. Healthcare providers often recommend that people who receive radioactive iodine treatment avoid eating foods that are high in iodine, including:

  • Iodized salt
  • Cereals
  • Grains
  • Certain bread
  • Shellfish
  • Certain fish
  • Dairy

Eating a variety of fruits and vegetables can help regardless of the treatment and can benefit many areas of health, including digestion and metabolism.

Hyperthyroidism and Pregnancy

People with hyperthyroidism who are or plan to become pregnant may require specialized medical care due to unique pregnancy risks associated with hyperthyroidism.

Hyperthyroidism while pregnant can increase the risks of:

Pregnancy may affect treatment options for hyperthyroidism. People who are pregnant or breastfeeding should not be treated with radioactive iodine. Additionally, people treated with radioactive iodine should not be around pregnant women for a few weeks or get pregnant within six months to a year of this treatment.

Radioactive iodine may also make it more challenging to get pregnant due to irregular periods or early menopause.

Outlook for Hyperthyroidism

The outlook of hyperthyroidism depends on the underlying cause, the person, and the severity of the condition. Treatment is not always required, and the condition may resolve independently. However, it tends to get worse in cases such as Graves' disease.

In general, hyperthyroidism is treatable and can be managed. Even when the thyroid is working normally, it is essential to continue regular care for life to maintain proper functioning.


Hyperthyroidism happens when the thyroid gland makes too much thyroid hormone, including T3 and T4, leading to symptoms such as nervousness and unintended weight loss. There are multiple causes, including Graves' disease and inflammation. Women are more likely to experience hyperthyroidism than men. Treatment options are available, and some may require medications for life.

The outlook of this condition is good, and it can be managed well with medications and other treatment options.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Ashley Olivine, Ph.D., MPH
Dr. Ashley Olivine is a health psychologist and public health professional with over a decade of experience serving clients in the clinical setting and private practice. She has also researched a wide variety psychology and public health topics such as the management of health risk factors, chronic illness, maternal and child wellbeing, and child development.