An Overview of Hyperthyroidism

Hyperthyroidism occurs when your thyroid gland produces too much thyroid hormone. It is sometimes also referred to as an "overactive” thyroid or, by the medical term, thyrotoxicosis.

When functioning normally, your thyroid—a small, butterfly-shaped gland in your neck—uses dietary iodine to produce thyroid hormone. The purpose of thyroid hormone is to regulate how your organs, glands, tissues, and cells use oxygen and energy.

The human body needs thyroid hormone in order to survive and function, but it needs to be the right amount.

What Are the Causes of Hyperthyroidism?

There are a number of health issues and conditions that result in a thyroid that overproduces thyroid hormone.

Autoimmune Graves’ Disease
This is the most common cause of hyperthyroidism. Graves' disease is an autoimmune disease where your immune system inappropriately produces antibodies, known as thyroid stimulating antibodies (TSI), that overstimulate your thyroid gland and cause it to overproduce thyroid hormone.

Autoimmune Hashimoto’s Disease
There are phases of Hashimoto’s disease where the thyroid gland can cause temporary hyperthyroidism.

Iodine-Excess Hyperthyroidism
Iodine overexposure/overconsumption can trigger or cause hyperthyroidism. Sources of iodine include iodine-based contrast tests and high doses of iodine supplementation, including iodine-rich herbs like bladderwrack and kelp.

Overdosage of Prescription Thyroid Hormone
If you take too much thyroid medication, by accident or intentionally, this can cause what's known as factitious hyperthyroidism. If your doctor prescribes a dosage that is too high, that results in iatrogenic hyperthyroidism.

Drug- and Supplement-Induced Hyperthyroidism
A number of drugs have been shown to cause hyperthyroidism. Some of the more well-known ones include interferon, dopamine, bromocriptine, high-dose steroids, and amphetamines. There are also supplements, especially some over-the-counter thyroid support supplements, that can cause hyperthyroidism. In violation of regulations, some over-the-counter supplements have been found to contain actual thyroid hormone. Other supplements that can potentially trigger hyperthyroidism include iodine, kelp, and bladderwrack.

Hyperfunctioning Thyroid Nodules/ Toxic Multinodular Disease
Thyroid nodules can sometimes become capable of producing thyroid hormone, apart from the hormone being produced by the gland itself. In some cases, these nodules produce too much thyroid hormone, causing hyperthyroidism. In a condition known as toxic multinodular disease, multiple nodules produce thyroid hormone and cause hyperthyroidism.

Transient Hyperthyroidism of Hyperemesis Gravidarum
Transient hyperthyroidism of hyperemesis gravidarum, or THHG, is a form of hyperthyroidism triggered by a severe morning sickness during pregnancy.

Some of the various types thyroiditis cause periods of hyperthyroidism. Postpartum thyroiditis, in particular, frequently starts with a hyperthyroid phase.

Pituitary-Induced Hyperthyroidism
The thyroid gland can become overstimulated and produce excessive amounts of thyroid hormone as a result of a malfunctioning and overactive pituitary gland.

Neonatal Hyperthyroidism
Neonatal hyperthyroidism is a type of hyperthyroidism in a newborn that is a result of elevated maternal thyroid stimulating immunoglobulin levels during pregnancy that cause the baby to be born with excess thyroid antibodies in their own system.

What Are the Risk Factors for Hyperthyroidism?

There are a number of risk factors for hyperthyroidism, but gender is perhaps the most important. Being a woman means you are eight to 10 times more likely than a man to develop a thyroid condition.

And while women are at a much higher risk of hyperthyroidism than men, there are some additional points where that risk is even greater for women, including:

  • During puberty
  • When you are currently pregnant
  • When you've had a child within the past year
  • When you are in perimenopause
  • When you are past menopause

Age: While hyperthyroidism can occur at any age, it is more common as you get older; in particular, it is more likely to occur after age 40.

Thyroid History: If you or family members have a history of any thyroid disease, especially goiter, nodules, or thyroiditis, this increases your risk of hyperthyroidism.

Autoimmune History: If you or family members have other autoimmune diseases—even if they are not autoimmune thyroid diseases like Graves’ disease and Hashimoto’s thyroiditis—you are at greater risk of developing hyperthyroidism.

Other Risk Factors: Other risk factors include the following:

  • Iodine excess (i.e. from supplementing with iodine or iodine-rich supplements)
  • Being a past or current smoker
  • Medications: Taking certain medications like interferon, dopamine, bromocriptine, high-dose steroids, and amphetamines
  • Hyperpituitarism: An over functioning pituitary gland (typically due to a benign tumor called an adenoma)

    What Are the Signs and Symptoms of Hyperthyroidism?

    Clinical Signs

    There are some observable signs of hyperthyroidism that can be measured, seen, or detected in a clinical examination by your practitioner. Some of these signs of hyperthyroidism include:

    • Goiter - the medical term for an enlarged thyroid gland that can be seen or felt
    • A visible or palpable lump in the area of your thyroid/neck
    • Evidence of increased blood flow to your thyroid, which your doctor can hear by stethoscope
    • A high heart rate, high blood pressure, higher-than-normal body temperature, heart palpitations, or changes in heart rhythm
    • Fast or hyperresponsive reflexes

    Common Symptoms

    Some other common hyperthyroidism symptoms you may experience include:

    • Fatigue, exhaustion, sluggishness, even after sufficient sleep
    • Insomnia, anxiety, panicky feelings
    • Feeling hot when others are cold, sweating more than usual, feeling unusually thirsty
    • Hoarse or gravelly voice
    • Aches, pains, or weakness in your joints, hands, and feet

    These lists, however, are just the tip of the iceberg. For a full overview of possible symptoms, as well as some that are unique to women, babies, and children, read our in-depth review: Symptoms and Signs of a Thyroid Condition.

    How Is Hyperthyroidism Diagnosed?

    Diagnosis of hyperthyroidism involves several key steps:

    A Clinical Examination

    During a clinical examination, your doctor should evaluate your personal and family history for thyroid and autoimmune disease, review your symptoms, and examine your thyroid manually. The doctor will also look for other clinical signs of hyperthyroidism, including a high pulse rate, high blood pressure, heart palpitations, changes to hair and skin texture, goiter (an enlarged thyroid), exaggerated reflexes, bulging eyes, and patchy skin on your legs, among others.

    Blood Testing

    Blood tests are used to diagnose hyperthyroidism. These tests include:

    • Thyroid Stimulating Hormone (TSH): When your thyroid is producing too much thyroid hormone, the TSH level drops. When you are hyperthyroid, this level will usually be below the reference range; if you are significantly hyperthyroid, it will be close to 0.
    • Free Thyroxine (Free T4): Your doctor should also evaluate your free T4, the unbound available form of this thyroid hormone. In hyperthyroidism, these levels will typically be in the high end of the reference range, or above the top cutoff of the range.
    • Free Triiodothyronine (Free T3): Your doctor should also measure your free T3 to get a picture of the unbound circulating levels of this active thyroid hormone. In hyperthyroidism, these levels will typically be in the high end of the reference range, or above the top cutoff of the range.
    • Thyroid Antibodies Testing: To determine if your hyperthyroidism is due to autoimmune disease, your doctor should also conduct antibodies testing, specifically, the thyroid stimulating immunoglobulin (TSI) levels. Elevated TSI can be indicative of Graves’ disease. Some doctors also test for elevated thyroid peroxidase antibodies (TPO) and thyroglobulin antibodies (TgAb), which, in some cases, may help pinpoint whether the hyperthyroidism is a temporary phase of Hashimoto’s disease.

    Imaging Tests

    There are a number of imaging tests that can be done to further evaluate your thyroid function. But the test most often used as part of the process of diagnosing hyperthyroidism is the specialized radioactive iodine uptake (RAI-U) test. In this test, a small dose of radioactive iodine is administered, and a follow-up scan can detect whether the thyroid—or nodules within the thyroid—is overproducing thyroid hormone.

    If you are hyperthyroid, your gland usually takes up higher amounts of iodine than normal, and that uptake is visible in an elevated result on the RAI-U test. A thyroid that takes up iodine is referred to as "hot" or overactive, versus a "cold" or underactive thyroid. If you have Graves' disease, the RAI-U will be elevated and show that your entire gland is hot. If you have thyroid nodules, RAI-U will show whether the nodules are hot and are producing thyroid hormone. If you are hyperthyroid due to a hot nodule, and not Graves' disease, the nodule will show up as hot, and the rest of your thyroid will be cold.

    Hot nodules may overproduce thyroid hormone but they are rarely cancerous. In someone with hyperthyroidism, the RAI-U would typically be normal only if hyperthyroidism is due to a pituitary tumor or taking too much thyroid medication.

    How Is Hyperthyroidism Treated?

    There are three key treatments for chronic hyperthyroidism and Grave's disease.

    Antithyroid Drug Treatment

    Antithyroid drugs help to regulate thyroid levels by making it more difficult for the body to use iodine to produce thyroid hormone or, in some cases, to block the conversion of T4 to T3. The preferred antithyroid drug in the Unite States is methimazole, which is also known by its brand name, Tapazole. (Carbimazole is a drug that metabolizes into methimazole and is known by its brand name Neo-Mercazole. It is more commonly used in Europe.)

    Propylthiouracil is usually abbreviated as PTU. There are no brand names of PTU in the United States, as only generic PTU is available. PTU inhibits the thyroid from using iodine to produce thyroid hormone and inhibits T4-to-T3 conversion. Due to some risks associated with PTU, methimazole is most often recommended, except during the first trimester of pregnancy, when methimazole is associated with risks of birth defects.

    Among the antithyroid drugs, methimazole is considered the first-line drug in most cases. This is because PTU has a higher risk of liver damage. PTU is recommended only in patients who have an allergy to methimazole (and during the first trimester of pregnancy.) If you are on PTU, your doctor should closely watch you for signs and symptoms of liver problems, especially during the first six months after initiation of therapy.

    All the antithyroid drugs can have some side effects, including rashes, itching, and hives. Some people may have this reaction to one of the drugs, but not have side effects with another drug.

    If symptoms are significant, you may not be a good candidate to continue with antithyroid drugs.

    There is a rare but serious side effect of antithyroid drugs, called agranulocytosis. This makes it hard for your body to produce enough white blood cells, which lowers your immunity and makes you more likely to get infections. If you develop a fever or a sore throat while taking antithyroid medications, it's crucial that you consult your doctor immediately to rule out agranulocytosis.

    In some cases, antithyroid drugs will allow you to achieve a remission of your hyperthyroidism. This means that thyroid levels return to the reference range and symptoms disappear. Your doctor may taper you off the antithyroid drugs. Keep in mind, however, that even after a remission, your hyperthyroidism may return, so periodic monitoring is important.

    Beta Blockers

    Beta blockers are not a stand-alone treatment for hyperthyroidism, but they are sometimes prescribed along with antithyroid drugs–or before or after RAI or thyroid surgery–to help relieve symptoms, including rapid heart rate, heart palpitations, and tremors. Common beta blockers include Inderal (propranolol), Tenormin (atenolol), and Lopressor and Toprol-XL (metoprolol), among others.

    Radioactive Iodine Treatment

    In the United States, radioactive iodine (RAI) is a common treatment for most people with Graves' disease and hyperthyroidism. Some other terms sometimes used to describe RAI include radioiodine ablation; radioactive iodine ablation; thyroid ablation; and ablation therapy. RAI is given as a single dose, in a capsule or drink, where it enters the thyroid, radiates thyroid cells, and damages and kills them. This shrinks the thyroid, slows down its function, and reverses hyperthyroidism.

    While the goal of RAI is to leave enough of the thyroid to have the gland function normally and produce normal levels of thyroid hormone, there are cases where the dose of RAI is not enough or is too much. When the dose was too low, you may continue to have hyperthyroid symptoms and, ultimately, may require a second RAI treatment. When the dose is too high, which is common, your thyroid will be left in a situation where it is unable to produce enough thyroid hormone. This means that you are now considered hypothyroid and will likely require lifelong thyroid hormone replacement drugs.

    It’s also important to note that if you are planning to conceive, doctors recommend waiting for six months to a year after RAI before getting pregnant. If you want to have a baby more quickly, you may want to discuss the option of surgery with your doctor.

    Many doctors in the United States emphasize RAI as the first—and sometimes the only—option for the treatment of hyperthyroidism. Keep in mind that outside the United States, long-term use of antithyroid drugs and surgery are considered equally valid options, so be sure to explore all of the options with your doctor.

    It’s also important to make sure that you are not rushed into RAI with hyperthyroidism that is temporary or transient, such as with Hashimoto’s disease or a postpartum thyroiditis. Be sure that your doctor is knowledgeable, has explained the cause of your hyperthyroidism, ruled out any transient/temporary hyperthyroidism, and is clear about why RAI is being recommended over other treatment options.

    Thyroid Surgery/Thyroidectomy

    Thyroid surgery is performed in some cases as a treatment for Graves’ disease and hyperthyroidism, especially if you cannot tolerate antithyroid drugs, or you want to get pregnant in the next year. Also, if you develop significant hyperthyroidism during pregnancy and cannot tolerate antithyroid drugs—or you require such high doses that the baby is being affected—surgery may be recommended, which is usually performed during your second trimester. Surgery is considered very effective and can provide rapid relief of symptoms to most patients, particularly when you have a large goiter and/or severe symptoms. Thyroidectomy to remove all or part of the thyroid gland is considered a safe surgery, as it has a low rate of complications when done by an experienced surgeon.

    Integrative/Functional Approaches to Hyperthyroidism

    On the medical side, some cutting-edge, integrative practitioners are using low-dose naltrexone (LDN), a safe, generic, and inexpensive drug, to lower antibodies. In addition, some physicians are using a new approach, autologous stem cell transplants, to help reduce antibodies and "reboot" the immune system.

    Integrative physicians, traditional Chinese medicine (TCM) practitioners, and naturopaths also offer some other approaches to address both the underlying autoimmunity that causes many cases of hyperthyroidism and the overactivity of the thyroid itself.

    Some of the herbs and supplements used to deal with autoimmune Graves' disease and hyperthyroidism include selenium, bugleweed, l-carnitine, Royal maca, valerian, ashwagandha, lemon balm, and B-complex. In many cases, these herbs and supplements do not replace your need for antithyroid drugs, but allow for lower—and therefore safer—doses of these drugs to be used.

    Active stress management is also highly recommended by many integrative practitioners to help calm heart- and blood pressure-related symptoms, as well as improve anxiety and nervousness that accompany hyperthyroidism. Active stress management approaches that may work include guided meditation, breath work, gentle yoga, Tai Chi, Qi Gong, or crafts like needlework, painting, or coloring.

    A word of caution: Untreated hyperthyroidism increases the risk for a dangerous condition known as thyroid storm, which can cause uncontrolled high blood pressure and heart rate, and lead to a stroke or heart attack. If you choose to work with a holistic or integrative practitioner on natural approaches, make sure it is someone who is highly reputable and knowledgeable about working with hyperthyroid patients. It also goes without saying that because of the risk, you should never consider hyperthyroidism a “do-it-yourself” project and attempt to treat yourself with over-the-counter herbs or supplements.

    A Healthy Life After Hyperthyroidism Treatment

    The permanent treatments for hyperthyroidism—RAI and surgery—usually result in you being hypothyroid, meaning that you will require lifelong thyroid hormone replacement drugs. It’s important, then, to be prepared by becoming knowledgeable about thyroid hormone replacement treatment and how to ensure that your treatment is optimal, not just designed to get your levels into the reference range while failing to relieve hypothyroidism symptoms.

    A good starting point is reading the many hypothyroidism-related articles here at Verywell that can help you live well. You may want to start with:

    A Word From Verywell

    Hyperthyroidism can be confusing and is often misdiagnosed. Symptoms such as anxiety, insomnia, irritability, weight loss, and heart palpitations are too often mistakenly attributed by both patients and doctors to anxiety or panic disorder, or even an eating disorder. If you have a family history, risk factors, and signs and/or symptoms of hyperthyroidism, it’s vitally important that you insist on comprehensive evaluation and testing. Don’t accept a mental health or eating disorder diagnosis without ruling out the possibility that you are hyperthyroid.


    Bahn, R., Burch, H, Cooper, D, et al. Hyperthyroidism and Other Causes of Thyrotoxicosis: Management Guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists."Endocrine Practice. Vol 17 No. 3 May/June 2011.

    Braverman, L, Cooper D. Werner & Ingbar's The Thyroid, 10th Edition. WLL/Wolters Kluwer; 2012.

    More From Verywell in Hyperthyroidism