Understanding Hyperthyroidism

Exploring Hyperthyroidism and its Causes, Risks, Symptoms, and Treatments

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Hyperthyroidism means that your 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. 


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 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 of the 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, 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 born with excess thyroid antibodies in their own system.


There are a number of risk factors for hyperthyroidism, but gender is perhaps the most important. Being a woman means you are eight to ten 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, and is more likely to occur after age 40.

Thyroid History–If you or family members have any a history of any thyroid disease, especially a history of 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 more risk of developing hyperthyroidism.

Other Risk Factors–Other risk factors include the following:

  • Iodine excess–if you are supplementing with iodine–or iodine-rich supplements like kelp and bladderwrack, you are at risk of developing hyperthyroidism.
  • If you are a past or current cigarette smoker you are at greater risk of developing hyperthyroidism.
  • Medications–taking certain medications like interferon, dopamine, bromocriptine, high-dose steroids, and amphetamines can increase your risk of hyperthyroidism.
  • Hyperpituitarism–an overfunctioning pituitary gland, typically due to a benign tumor called an adenoma -– is a risk for hyperthyroidism.


Clinical Signs

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

  • Goiter–an enlarged thyroid
  • Palpable enlargement in your thyroid gland
  • A visible or palpable lump in your neck
  • Evidence of increased blood flow to the thyroid–detected by stethoscope
  • An unusually high heart rate, and/or elevated blood pressure
  • Evidence of heart palpitations, or rhythm irregularities
  • Fast or hyperresponsive reflexes
  • Chronic or severe diarrhea
  • Higher-than-normal body temperature
  • Rapid weight loss
  • Bulging in your eyes (known as proptosis)
  • Red, dry, swollen, puffy or water eyes
  • "Lid lag"–when your upper eyelid doesn't smoothly follow downward movements of the eyes when you look down
  • Unusual rashes or blister-like bumps on your forehead and face (known as malaria bumps)
  • spider veins in face and neck area
  • Unusually smooth and young-looking skin
  • Thinning, fine or shedding hair
  • Tremors or shakiness in your hands, or hyperkinetic movements–i.e., table drumming, tapping feet, jerky movements (often more severe in children)
  • Swollen fingertips (a condition known as acropachy, (a separation of fingernail from your underlying nail bed (called and onycholysis, or Plummer's nails)
  • Lesions on your shins, or patches of thickened skin, known as pretibial myxedema or dermopathy


There are some hyperthyroidism signs that are unique to women:

  • You are pregnant but losing weight
  • You are rapidly losing weight after having a baby
  • You are pregnant and having excessive nausea or vomiting
  • You have a history of irregular menstrual cycles
  • You are experiencing longer periods of time between menstrual periods
  • You are skipping periods
  • Your periods are lighter and shorter
  • You have history of infertility or recurrent miscarriage

Common Symptoms

Some other common hyperthyroidism symptoms you may experience include:

  • You feel fatigued, rundown, sluggish, and exhausted, even after a lengthy sleep
  • You have insomnia
  • You feel anxious, restless, or inexplicably irritable
  • You are easily startled
  • You feel hot when others feel cold
  • You are sweating more than usual
  • You are thirstier than usual
  • You have panicked feelings or full panic attacks
  • You have tremors, especially in your hands
  • Your hair is breaking, brittle, or falling out
  • Your skin is unusually smooth
  • You have a hoarse or gravelly voice
  • You have aches and pains in joints, hands, and feet
  • Your upper arms and lower legs feel weak
  • Your eyes feel gritty, dry, and sensitive to light
  • You are experiencing double vision
  • Your eyes are bulging, or you have an inability to close your eyelids
  • Your neck or throat feels different, and ties, scarves or turtlenecks feel uncomfortable
  • You have unexplained weight loss, with no change in diet or exercise
  • You have an increased appetite and food intake, but no corresponding weight gain
  • You are having an elevated heart rate, high blood pressure, and/or heart palpitations
  • You have reddish-brown lesions on your shins and lower legs
  • Your fingers nails break easily
  • You have a swelling and widening or your fingertips and toes

Babies and Children

In babies and children, common symptoms include:

  • Easy startling
  • Attention deficit hyperactivity disorder (ADHD) type symptoms
  • Hyperactivity or temper tantrums
  • Hyperkinetic movements such as drumming on tables, jerking of leg, tapping feet
  • Delayed puberty
  • Difficulty gaining weight
  • Big appetite along with weight loss
  • Trouble concentrating
  • Poor school performance
  • Jumpiness, trembling hands
  • Sweating
  • Sleep problems
  • A wide-eyed stare


Diagnosis of hyperthyroidism involves several key steps:

A Clinical Examination

During a clinical examination, your doctor will evaluate your personal and family history for thyroid and autoimmune disease, review your symptoms, and should 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, and when you are hyperthyroidism, this level usually will be below the reference range, or if you are significantly hyperthyroid, 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.

Radioactive Iodine Uptake (RAI-U) Test

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.


There are three key treatments for Graves’ disease and chronic hyperthyroidism.

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 U.S. 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.

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 the other 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 you are taking antithyroid medications, it's crucial that you consult your doctor immediately to rule out agranulocytosis. 

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. 

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 heartrate, heart palpitations, and tremors.  Common beta blockers include propranolol (Inderal), atenolol (Tenormin) metoprolol (Lopressor, Toprol-XL), 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 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 U.S. emphasize RAI as the first–and sometimes the only option–for the treatment of hyperthyroidism. Keep in mind that outside the U.S., 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, and 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, with a low rate of complications when done by an experienced surgeon.


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 herb and supplements that are used to deal with autoimmune Graves' disease and hyperthyroidism include selenium, bugleweed, l-carnitine, Royal maca, valerian, ashwagandha, lemon balm, B-complex. In many cases, these herbs and supplements do not replace your need for antithyroid drugs, but rather, 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 the heart and blood pressure related symptoms, as well as relaxed anxiety and nervousness that accompany hyperthyroidism. Active stress management approaches that may work include guided meditation, breathwork, 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 and 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.


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 help you live well.

Another helpful resource is this advice offered in 10 ways to be a smart thyroid patient

It's also particularly important to make sure you are choosing and working with doctors, and know when to get a second opinion, what the shortage of endocrinologists means for your thyroid care, and are aware of five things you should never say to your doctor.


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, 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.

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