Hyperthyroidism

Overview

What is hyperthyroidism?

Hyperthyroidism is a condition where your thyroid creates and releases more hormones to your body than you need. This is also called an overactive thyroid. The main hormones made by the thyroid include triiodothyronine (T3) and thyroxine (T4). Having hyperthyroidism can impact your entire body. Picture something related to the word “hyper.” Most likely, you just thought of something that’s fast or full of a lot of energy. When you have hyperthyroidism, the extra hormones can speed up your metabolism. Metabolism is the process that transforms the food you put in your body into energy that helps your body function. When you have hyperthyroidism, your metabolism is launched into high-speed. This might cause you to feel your heart beating faster, experience anxiety and nervousness, and have an increased appetite.

Hyperthyroidism can affect your entire body and is a condition that needs to be treated by a healthcare provider.

What does my thyroid do?

Located at the front of your neck, the thyroid is a butterfly-shaped gland. Glands are organs that can be found all over your body. They create and release hormones — substances that help your body function and grow. The thyroid gland plays a big part in many of your body’s main functions. Your thyroid gland regulates your body temperature and controls your heart rate and metabolism.

When your thyroid gland is working correctly, your body is in balance and all of your systems function properly. If your thyroid stops working in the way it’s meant to — creating too much or too little of thyroid hormones — it can impact your entire body.

Who is most likely to get hyperthyroidism?

Both men and women can have hyperthyroidism. However, it’s more commonly seen in women. Some factors that could increase your risk of developing hyperthyroidism can include:

How common is hyperthyroidism?

Hyperthyroidism happens in about 1% of people in the United States.

Symptoms and Causes

What causes hyperthyroidism?

There are several different medical conditions that can cause hyperthyroidism. These medical conditions can include:

  • Graves’ disease: In this disorder, your immune system attacks the thyroid. This makes the thyroid create too much thyroid hormone. Graves’ disease is a hereditary condition (passed down through a family). If a member of your family has Graves’ disease, there’s a chance others in the family could have it too. It’s more common in women than men. Graves’ disease is the most common cause of hyperthyroidism, making up about 85% of cases.
  • Thyroid nodules: A thyroid nodule is a lump or growth of cells in the thyroid gland. The nodule is able to produce more hormones than your body needs. Such nodules are rarely cancerous.
  • Thyroiditis: This is a general term that refers to swelling (inflammation) of your thyroid. This inflammation can be caused by an infection or a problem with your immune system. When the thyroid is inflamed, it can leak hormones, resulting in higher levels of hormones than your body needs. Thyroiditis can happen after the delivery of a baby (postpartum thyroiditis) or from taking drugs like interferon and amiodarone (a heart medication).
  • Iodine: If you consume too much iodine (through your diet or medications), it can actually cause your thyroid to produce more thyroid hormone. Iodine is a mineral that your thyroid uses to create thyroid hormone. Receiving intravenous iodinated contrast (iodine “dye”) may also cause hyperthyroidism.

Can I develop hyperthyroidism during or after pregnancy?

During early pregnancy, your body needs to produce more thyroid hormones than normal to help the baby develop. These hormones are particularly important for your baby’s brain and nervous system. Having thyroid hormone levels that are a little higher than normal is alright, but if your levels increase dramatically, your healthcare provider may need to form a treatment plan. High levels of hyperthyroidism can impact not only you, but also your baby.

It can be difficult to diagnose hyperthyroidism during pregnancy because your thyroid hormone levels naturally increase and the other symptoms of pregnancy mask signs of hyperthyroidism.

There is also a condition called postpartum thyroiditis that happens after your baby is born. This condition can happen during the first year after birth. It’s more common in women who also have type 1 diabetes. Postpartum thyroiditis can start out as hyperthyroidism (over-producing thyroid hormones) and then shift into hypothyroidism. However, this pattern doesn’t happen to every woman with postpartum thyroiditis. If you begin having symptoms of a thyroid disease during or after pregnancy, talk to your healthcare provider.

What are the symptoms of hyperthyroidism?

There are many symptoms of hyperthyroidism and they can impact your entire body. You may experience some of these symptoms and not others, or many of them at the same time. Symptoms of hyperthyroidism can include:

  • Rapid heartbeat (palpitations).
  • Feeling shaky, nervous.
  • Weight loss.
  • Increased appetite.
  • Diarrhea and more frequent bowel movements.
  • Double vision.
  • Thin skin.
  • Menstrual changes.
  • Intolerance to heat and excessive sweating.
  • Sleep issues.
  • Swelling and enlargement of the neck from an enlarged thyroid gland (goiter).
  • Hair loss and change in hair texture (brittle).
  • Bulging of the eyes (seen with Graves’ disease).
  • Muscle weakness.

What complications of hyperthyroidism can affect my body?

Hyperthyroidism can impact many parts of your body. Different systems, ranging from your vascular system (heart) to your skeletal system (bones) can all be affected if you have an overactive thyroid.

Heart

When you have hyperthyroidism, it may feel like your heart is beating very quickly. This rapid heartbeat is a symptom of the condition that’s caused by your fast metabolism. The body is running faster than normal when you have hyperthyroidism, making you feel like your heart is racing. Having an irregular heartbeat can increase your risk of different medical conditions, including stroke.

Bones

The bones are the support structure for your body. When you have unchecked high levels of thyroid hormones, your bones can actually become brittle. This can lead to a condition called osteoporosis.

Eyes and Skin

Hyperthyroidism can be caused by a medical condition called Graves’ disease. This disease can affect both your eyes and skin. It can cause you to have several eye problems, including:

  • Bulging eyes.
  • Vision loss.
  • Double vision and light sensitivity.
  • Redness and swelling of the eyes.

Graves’ disease can also cause your skin to become red and swollen. This is particularly noticeable on the feet and shins.

Another complication of hyperthyroidism is something called a thyroid storm (thyrotoxic crisis). This is a sudden and dramatic increase in your symptoms. When this happens, your heart may beat even faster than normal and you may develop a fever. A thyroid storm is an emergency situation.

Diagnosis and Tests

How is hyperthyroidism diagnosed?

Your healthcare provider will diagnose hyperthyroidism in several ways, including:

  • A physical exam of your neck to see if the thyroid is larger than normal.
  • Blood tests to look for high levels of thyroid hormone in your body.
  • Imaging tests to look at your thyroid.

Physical Exam

During a physical exam, your healthcare provider will gently feel your neck to check the size of your thyroid gland. This is a simple and quick process that can be done in your provider’s office. The provider will also examine the eyes, the heart and the skin.

Blood Tests

Your healthcare provider may take a blood sample to look for high levels of thyroid hormone. This is called thyroid function testing. When you have hyperthyroidism, levels of the thyroid hormones T3 and T4 are above normal and thyroid stimulating hormone (TSH) is lower than normal.

Imaging Tests

Taking a look at the thyroid can help to diagnose hyperthyroidism and the possible cause (often Graves’ disease). Your provider could use a few tests to look at your thyroid. One test is called a thyroid scan and radioactive iodine uptake test. A thyroid scan uses small amounts of radioactive material to create images of your thyroid.

Another test is a thyroid ultrasound. An ultrasound is a non-invasive procedure that allows your provider to look at your thyroid on a screen. This test is used if your provider is looking for thyroid nodules.

Imaging tests allow your provider to get a sense of the size and shape of the thyroid, as well as if there are any thyroid nodules. The scan can tell your provider if the thyroid is overactive and making too much thyroid. Often, seeing an increased radioactive iodine uptake on this scan can help diagnose Graves’ disease. If the thyroid is inflamed (swollen), it could be thyroiditis. In this case, there will be no radioactive iodine uptake in the neck.

Management and Treatment

How is hyperthyroidism treated?

There are many treatment options for hyperthyroidism. Depending on the cause of your hyperthyroidism, some options may be better for you over the long-term. Your healthcare provider will discuss each option with you and help you determine the best treatment for you.

Treatment options for hyperthyroidism can include:

  • Anti-thyroid drugs methimazole (Tapazole) or propylthioracil (PTU): These drugs block the ability of the thyroid to make hormones. They offer rapid control of your thyroid.
  • Radioactive iodine: Radioactive iodine is taken by mouth and absorbed by the overactive thyroid cells. The radioactive iodine damages these cells, and causes your thyroid to shrink and thyroid hormone levels to go down over a few weeks. This usually leads to permanent destruction of the thyroid, which will cure hyperthyroidism. Most patients who receive this treatment have to take thyroid hormone drugs for the rest of their lives to maintain normal hormone levels.
  • Surgery: Your healthcare provider may remove the thyroid gland through surgery (thyroidectomy). This will correct your hyperthyroidism, but it will usually cause hypothyroidism (an underactive thyroid). Patients who have a thyroidectomy have to take thyroid supplements to keep hormone levels normal.
  • Beta blockers: These drugs block the action of thyroid hormones on the body. They do not change the amount of hormones in your blood, but they can help control symptoms like rapid heartbeat, nervousness, and shakiness that are caused by hyperthyroidism. This treatment isn’t used alone and is usually paired with another option to treat hyperthyroidism over the long-term.

How long does it take to treat hyperthyroidism?

The amount of time it takes to treat hyperthyroidism can change depending on what caused the condition. If your healthcare provider treats your condition with anti-thyroid medications (methimazole or propylthioracil) your hormone levels should drop to a controllable level in about six to 12 weeks. Your healthcare provider may decide to give you high doses of iodine drops (not radioactive) which would normalize thyroid levels in seven to 10 days. However, this is short-term solution and you will most likely need a more permanent solution like surgery. Though you may need to wait for a period of time to be scheduled for thyroid surgery (thyroidectomy), this is a very effective and definitive way to treat hyperthyroidism. It’s considered a permanent solution for hyperthyroidism.

Are there any risks to hyperthyroidism treatments?

With most treatments, there are also risks of side effects. It’s important to talk to your healthcare provider and weigh all of the pros and cons before deciding on a treatment plan. Some of these risks include:

  • Medication side effects: The two medications that can be used to treat hyperthyroidism are methimazole and propylthioracil. These drugs can cause several side effects. One side effect is potential liver damage. This can happen to people of any age. In pregnant women, this medication can pass from mom to the baby through the placenta. This could cause hypothyroidism or the development of a goiter in the unborn baby. Expectant mothers are closely monitored because of this side effect. In all patients there’s also a possibility of an allergic reaction to these medications, but this is very rare.
  • Radioactive materials: Whenever radiation is involved, there’s a possible side effect of cancer. Currently, there’s no link between using radioactive iodine to treat hyperthyroidism and developing cancer. This is considered a low risk and unlikely. One risk that is known is between a pregnant or breastfeeding mother and her baby. Women shouldn’t take radioactive iodine while pregnant or breastfeeding because it can affect the baby’s thyroid glands. Sometimes, you can lose sensation in your mouth after radioactive iodine (RAI) therapy. This is actually common. But don’t worry, even though it can last for up to a year, the sensation does come back to your mouth over time.
  • Surgery: There are always certain risks linked to surgery, like infection and bleeding. Surgery is generally considered a very effective treatment for hyperthyroidism. In rare situations, complications like paralysis of the vocal cords (inability to speak) and damage to your parathyroid glands can happen, which results in low calcium in the blood.

After treatment, you will most probably need to take replacement thyroid hormone for the rest of your life. This is because some of these treatments – especially surgery – reduce your thyroid hormone levels to very low levels or eliminate this hormone by removing your thyroid. You’ll need to re-introduce the thyroid hormones back into your system by taking regular medication.

Can I get hypothyroidism from my hyperthyroidism treatment?

You can get hypothyroidism (a condition where your body doesn’t produce enough thyroid hormone) from hyperthyroidism treatments. This is sometimes the goal of a healthcare provider. In hypothyroidism, the amount of thyroid hormone needs to be boosted. This can be done with medications that you regularly take. Adding hormones to your body is more manageable than trying to get your body to decrease the amount of thyroid hormone it creates.

Can hyperthyroidism cause female infertility?

One of the symptoms of hyperthyroidism in women can be irregular menstrual cycles (periods). The imbalance of thyroid hormone can impact all parts of your body. Some women actually start reaching out to their healthcare provider because of issues becoming pregnant and then learn about a thyroid condition.

Prevention

Can hyperthyroidism be prevented?

In most cases, hyperthyroidism cannot be prevented. It can be passed through a family (Graves’ disease) or appear when there’s an increase in the amount of thyroid hormone produced by your body (during or after pregnancy). If members of your family have Graves’ disease, talk to your healthcare provider about getting tested.

Outlook / Prognosis

Can hyperthyroidism be cured?

Yes, there is a permanent treatment for hyperthyroidism. Removing your thyroid through surgery will cure hyperthyroidism. However, once the thyroid is removed, you will need to take thyroid hormone replacement medications for the rest of your life. Your body still needs thyroid hormones, just not at such high levels as you have in hyperthyroidism. Though you will need to regularly take the medication and check in with your healthcare provider regularly, this is a manageable form of thyroid disease which allows you to live a normal life.

Last reviewed by a Cleveland Clinic medical professional on 04/19/2020.

References

  • US Department of Health and Human Services, National Institute of Diabetes and Digestive and Kidney Diseases. Hyperthyroidism (Overactive Thyroid). (https://www.niddk.nih.gov/health-information/endocrine-diseases/hyperthyroidism?dkrd=hispt0298) Accessed 4/20/2020.
  • American Thyroid Association. Hyperthyroidism (Overactive). (http://www.thyroid.org/hyperthyroidism/) Accessed 4/20/2020.
  • Merck Manual Consumer Version. Hyperthyroidism. (https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/thyroid-gland-disorders/hyperthyroidism) Accessed 4/20/2020.
  • US Department of Health and Human Services, National Institute of Diabetes and Digestive and Kidney Diseases. Thyroid Disease & Pregnancy. (https://www.niddk.nih.gov/health-information/endocrine-diseases/pregnancy-thyroid-disease) Accessed 4/20/2020.

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