Hyperthyroidism, also called overactive thyroid, is a condition where your thyroid makes and releases high levels of thyroid hormone. This condition can make your metabolism speed up. Symptoms of hyperthyroidism include a rapid heartbeat, weight loss, increased appetite and anxiety. Hyperthyroidism can be treated with antithyroid drugs, radioactive iodine, beta blockers and surgery.
Hyperthyroidism is a condition in which your thyroid creates and releases more hormones than you need. This is also called overactive thyroid. The main hormones your thyroid makes include triiodothyronine (T3) and thyroxine (T4).
Hyperthyroidism can affect your entire body and is a condition that needs to be treated by a healthcare provider.
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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. Some of your glands 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, including:
When your thyroid gland is working correctly, your body is in balance, and all of your systems function properly. If your thyroid stops working the way it’s meant to — creating too much or too little thyroid hormones — it can impact your entire body.
Hyperthyroidism and hypothyroidism are medical conditions that both have to do with the amount of thyroid hormone your thyroid makes and releases — the difference is how much.
Picture something related to the word “hyper.” Most likely, you just thought of something fast or full of a lot of energy. When you have hyperthyroidism, your thyroid is overactive and produces and releases too much thyroid hormone.
In the medical world, the prefix “hypo-” means “low” or “not enough.” When you have hypothyroidism, your thyroid is underactive and doesn’t make and release enough thyroid hormone that your body needs.
Anyone can have hyperthyroidism, but it’s more common in females.
Hyperthyroidism is relatively rare. Approximately 1% of people in the United States have 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:
Medical conditions and situations that can cause hyperthyroidism include:
Your healthcare provider can diagnose hyperthyroidism in several ways, including:
If you’re experiencing symptoms of hyperthyroidism, your healthcare provider’s may check the following during a physical exam in their office:
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.
Taking a closer look at your thyroid can help your provider diagnose hyperthyroidism and the possible cause of it. Imaging tests your provider could use to examine your thyroid include:
There are many treatment options for hyperthyroidism. Depending on the cause of your hyperthyroidism, some options may be better for you. Your healthcare provider will discuss each option with you and help you determine the best treatment plan.
Treatment options for hyperthyroidism include:
The amount of time it takes to treat hyperthyroidism can change depending on what caused it. If your healthcare provider treats your condition with antithyroid medications (methimazole or propylthiouracil) your hormone levels should drop to a healthy 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 a short-term solution, and you'll most likely need a more permanent solution like surgery. Though you may need to wait 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.
With most treatments, there are also risks of side effects. It’s important to talk to your healthcare provider and weigh all of the advantages and disadvantages before deciding on a treatment plan. Some of these risks include:
After treatment, you’ll most likely 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 reintroduce the thyroid hormones back into your system by taking regular medication.
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.
Complications from untreated or undertreated hyperthyroidism include:
If you’re experiencing symptoms of hyperthyroidism, it’s important to see your healthcare provider so they can determine a proper diagnosis and recommend treatment.
Some factors that could increase your risk of developing hyperthyroidism can include:
Hyperthyroidism is a manageable and treatable condition, and most people do well with treatment. While some forms of treatment require you to take medication for the rest of your life, your thyroid hormone levels will be normal.
Unfortunately, untreated hyperthyroidism caused by Graves’ disease may get worse over time and cause complications. If you have Graves’ disease, ask your healthcare provider questions about how you can best manage your condition.
Yes, there is a permanent treatment for hyperthyroidism. Removing your thyroid through surgery or destroying your thyroid through medication will cure hyperthyroidism. However, once your thyroid is removed or destroyed, you’ll 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'll need to take the medication and check in with your healthcare provider regularly, this is a manageable form of thyroid disease.
Thyroid storm (thyroid crisis or thyrotoxic crisis) is a rare but serious complication of hyperthyroidism. It happens when your thyroid makes and releases a large amount of thyroid hormone in a short amount of time. Thyroid storm is a life-threatening emergency that requires immediate medical attention.
Symptoms of thyroid storm include:
A complication of Graves’ disease, one of the causes of hyperthyroidism, is called Graves’ eye disease (Graves’ ophthalmopathy). This condition can usually not be prevented. Graves’ eye disease can cause the following complications:
If you’re experiencing signs and symptoms of hyperthyroidism, it’s important to see your healthcare provider so they can assess your condition and recommend treatment.
If you’ve already been diagnosed with hyperthyroidism, you’ll likely need to see your provider regularly to make sure your treatment is working.
If you’re experiencing signs of thyroid storm, a complication of hyperthyroidism, such as a high fever and a very fast heart rate, get to the nearest hospital as soon as possible.
One of the symptoms of hyperthyroidism can be irregular menstrual cycles (periods), which can make it difficult to get pregnant. Some people actually start reaching out to their healthcare provider because of issues becoming pregnant and then learn about a thyroid condition.
During early pregnancy, your body needs to produce more thyroid hormones than normal to help the developing fetus. These hormones are particularly important for its 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 thyroid hormones can impact not only you but also the fetus.
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.
Eating too many iodine-rich or iodine-fortified foods in your diet may cause hyperthyroidism or make it worse in some cases.
If you have hyperthyroidism, your healthcare provider may recommend certain changes to your diet. Always consult your provider or a registered dietician before making drastic changes to your diet. If you take medication for your hyperthyroidism, always take the amount prescribed by your provider.
According to the National Institutes of Health (NIH), the recommended daily dose of iodine is about 150 micrograms (mcg). The daily dose is higher for pregnant people. A low-iodine diet requires even less.
Seafood has the most iodine. Just 1 gram of seaweed contains 23.2 micrograms (mcg), or .02 milligrams (mg).
If your provider or dietician has recommended a low-iodine diet, try to avoid the following seafood and seafood additives:
Other foods have high amounts of iodine, including:
Hyperthyroidism is a type of thyrotoxicosis. Hyperthyroidism happens specifically when your thyroid gland both produces and releases excess thyroid hormone. Thyrotoxicosis happens when you have too much thyroid hormone in your body in general. You could have too much thyroid hormone by taking too much thyroid medication, for example. This would be thyrotoxicosis, not hyperthyroidism.
A note from Cleveland Clinic
Getting a new diagnosis can be stressful. The good news is that hyperthyroidism is a manageable and treatable condition. If you’re experiencing symptoms of hyperthyroidism or have certain risk factors, such as a family history of Graves’ disease, be sure to contact your healthcare provider. They can have you undergo some simple tests to see if your thyroid is making too much thyroid hormone.
Last reviewed by a Cleveland Clinic medical professional on 10/19/2021.
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