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Hyperthyroidism (overactive thyroid) is a common thyroid disorder, but many people don’t know much about it. 

At Banner Health, we’re here to help you better understand hyperthyroidism and make decisions about your thyroid health. Learn what causes this thyroid disorder, its symptoms and how it can be treated.

What is hyperthyroidism?

The thyroid is a small butterfly-shaped gland in your neck. It plays an important role in how your body uses energy – a process called metabolism. Your thyroid controls your metabolism by making certain hormones. These hormones also help balance your body temperature and keep your organs (like your heart and brain) and muscles working well.

Hyperthyroidism is a medical condition when your thyroid gland makes too many thyroid hormones. When there are too many of them, your body works faster than it should.

How is hyperthyroidism different from hypothyroidism?

Imagine your thyroid hormones as tiny messengers that tell your body how fast or slow to do things. Hyperthyroidism and hypothyroidism are the opposite extremes.

Hyperthyroidism is when your thyroid produces too much thyroid hormone and causes your body to work overtime. Hypothyroidism is an underactive thyroid, meaning it does not make enough thyroid hormones. This causes parts of your body to slow down. 

What are the symptoms of hyperthyroidism?

Symptoms are different for each person. Sometimes, symptoms may go unnoticed. Other times, they come on suddenly over a few days or weeks. 

In general, hyperthyroidism will make you feel like your body is speeding up. Common symptoms include:

  • Fast heart rate
  • Unintentional weight loss, despite eating normally
  • Shaky or trembling hands 
  • Increased sensitivity to heat
  • Anxiety and mood swings
  • Eye problems, such as double vision or bulging eyes
  • Problems falling or staying asleep (insomnia)
  • High blood pressure
  • Increased frequency of bowel movements or diarrhea

What causes hyperthyroidism?

The main cause of hyperthyroidism is an autoimmune disorder called Graves’ disease. Graves’ disease happens when the body’s immune system attacks the thyroid gland. When this happens, the thyroid works harder than it needs to and makes extra thyroid hormones.

However, Graves’ disease is not the only cause of hyperthyroidism. Other conditions that can cause it include:

  • Overactive thyroid nodules (toxic adenoma, toxic multinodular goiter and Plummer disease): Small lumps (nodules) can form inside the thyroid gland. These lumps are usually not cancerous, but one or more may produce too many thyroid hormones. 
  • Thyroiditis: This condition happens when the thyroid gland gets swollen and inflamed. The inflammation can cause extra thyroid hormones to leak into your bloodstream. Sometimes this can occur because of an autoimmune disorder, a medication or an infection, such as a virus or bacteria. Other times, the reason is unclear.
  • Too much thyroid hormone medicine: As other hormones in your body change, they can affect your thyroid. Therefore, if you’re taking medication for an underactive thyroid (hypothyroidism), it’s important to have your thyroid tested every six months to make sure you are taking the right dose.
  • Too much iodine: Eating foods or taking supplements or medications that contain too much iodine may cause the thyroid to make too much thyroid hormone. 

Am I at risk for hyperthyroidism?

Several conditions can increase your risk of developing hyperthyroidism. Here are some to know about:

  • Family history: If you have close family members with a history of thyroid disease, such as Graves’ disease, your risk of developing hyperthyroidism may be higher.
  • Personal history of thyroid disease: If you’ve had previous thyroid issues, such as thyroid nodules, you may be more at risk for developing the disorder.
  • Pernicious anemia: This condition is when your body can’t absorb enough vitamin B12. It’s been connected to a higher chance of getting thyroid diseases.

Other risk factors for hyperthyroidism include a recent pregnancy, smoking and possibly stress. 

How is hyperthyroidism diagnosed?

To diagnose hyperthyroidism, your health care provider will review your medical history and perform a physical exam. They may check for an enlarged thyroid gland, fast heartbeat, eye changes, shakiness in your hands and moist skin.

Because many of the symptoms of hyperthyroidism are the same as other diseases, your provider may use several tests to confirm the diagnosis: 

  • Blood tests: These tests measure the levels of thyroid hormones, including triiodothyronine (T3) and thyroxine (T4), as well as thyroid-stimulating hormone (TSH). High levels of T3 and T4 and low levels of TSH are signs of hyperthyroidism.
  • Imaging tests: Thyroid scans help your provider look closer at your thyroid. Your provider may also do a radioactive iodine uptake test. This test measures your thyroid’s ability to take in iodine. If your thyroid takes in too much, you may produce too much thyroid hormone.

How is hyperthyroidism treated?

Once your provider confirms your hyperthyroidism, they’ll talk about the best ways to treat it. The main goals of treatment are to control the extra thyroid hormone and ease your symptoms. 

Here are some common ways to do it:

  • Medication: You might take medicines called anti-thyroid drugs, like methimazole or propylthiouracil. They help slow down how much thyroid hormone your thyroid gland produces. Sometimes, your provider may also prescribe beta blockers to help with symptoms like a fast heartbeat or anxiety.
  • Radioactive iodine therapy (RAI): In this treatment, you swallow a radioactive iodine pill that slowly makes the thyroid work less. RAI is often used to treat Graves’ disease, but it is not recommended for pregnant or breastfeeding people due to radiation.
  • Surgery (thyroidectomy): In some cases, when other treatments do not work or are unsuitable for you, you might need surgery to remove part of or all of your thyroid gland. 

After surgery or RAI, you must take a small daily pill of thyroid medication for the rest of your life to keep your body working properly.

What can happen if hyperthyroidism is not treated?

If you don’t get treatment or manage hyperthyroidism properly, it can lead to some serious issues, including:

  • Heart failure: Your heart works harder when your pulse and blood pressure are high, which can eventually lead to heart failure.
  • Brittle bones (osteoporosis): Too much thyroid hormone can prevent your bones from taking in calcium. This causes your bones to be weaker and more prone to fracture.
  • Long-term eye problems: If you have Graves’ disease and don’t treat your hyperthyroidism, it can cause serious eye problems like double vision, eye pain and even vision loss.
  • Infertility: Too much thyroid hormone can make it harder to get pregnant. It can also be harmful to pregnant people and their babies during pregnancy.
  • Thyroid storm: This is very rare but extremely dangerous. It is when your thyroid becomes extremely overactive, causing a high fever, rapid heart rate and organ failure. Thyroid storm requires immediate emergency care. Call 911 if you or someone else experience these symptoms.

What is the long-term outlook for hyperthyroidism?

Hyperthyroidism is a lifelong condition, but most people can lead healthy lives with early diagnosis, treatment and monitoring. 

Here are some steps you can take:

  • Stay healthy: Eat well, exercise regularly, maintain a healthy weight and manage stress. These things are good for your overall health, including your thyroid. Quit smoking and limit alcohol.
  • Take your medication as prescribed: If your provider gives you medicine for hyperthyroidism, it’s important to take it every morning. Ask your provider about foods and supplements (like soy products, iron and calcium) that you should avoid taking at the same time as your thyroid medication.
  • Check your thyroid regularly: Work with your health care team to ensure your thyroid remains stable and you are on the right treatment.

Schedule an appointment

Take control of your thyroid health today by scheduling an appointment with one of our endocrinology specialists at Banner Health.