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What Is Hyperthyroidism?

Causes, symptoms, diagnosis, treatments, and support

Endless energy, unexplained weight loss—the initial symptoms of an overactive thyroid are often seen as “good” symptoms. That’s why hyperthyroidism is one of the most underdiagnosed endocrine conditions. But if left unchecked, it can lead to serious complications. We’re here to empower you with clear answers to all your hyperthyroid questions. 

Definition Causes | Symptoms | Diagnosis | Treatments | Complications Fast Facts | Risk Factors | Support 

Featured Voices: 
Debbie Chen MDBrenessa Lindeman MD, and Caroline T. Nguyen MD

What is hyperthyroidism?

Hyperthyroidism is the abnormal function of your thyroid gland, an organ located in the front of your neck that releases hormones to regulate your body’s use of energy. In other words, if you have high thyroid levels, it means that your thyroid gland is overactive and makes more thyroid hormones than your body needs, which causes hyperthyroidism.

The hormones produced by your thyroid gland are thyroxine (T4) and triiodothyronine (T3), and they play an important role in the way your entire body functions. For this reason, when there is an imbalance, such as high T4, it can have far-reaching effects on almost every aspect of your health.

Hyperthyroidism Fast FactsInfographic by Lauren Hunter

Thyroid hormones control your:

  • metabolism
  • breathing
  • heart rate
  • nervous system
  • weight
  • body temperature

When your thyroid gland is overactive, your body’s processes speed up. This acceleration can bring about hyperthyroidism symptoms such as:

  • nervousness
  • anxiety
  • rapid heartbeat
  • hand tremors
  • excessive sweating
  • weight loss
  • difficulty sleeping


Hyperthyroidism Causes

  • Graves’ disease. The most common cause of hyperthyroidism, Graves’ disease is an autoimmune disorder that results in your body creating too much thyroid hormone. About 1% of the U.S. population is affected by it.
  • Overactive thyroid nodules. Lumps that grow on your thyroid gland and amp up thyroid hormone production.
  • Thyroiditis. This is inflammation of your thyroid, and it can arrive in three different ways:
    • Subacute: A painful, enlarged thyroid, possibly from a virus or bacteria.
    • Postpartum: Occurs after a woman gives birth.
    • Silent: A painless, possibly enlarged thyroid, likely from an autoimmune condition.
  • Increased iodine consumption. Some foods and medications contain iodine, and too much can over-stimulate your thyroid.
  • Increased thyroid hormone medicine intake. This sometimes happens to patients who are being treated with thyroid hormones to correct hypothyroidism (underactive thyroid gland).

Who’s at risk for hyperthyroidism?

According to the National Institute of Health (NIH), hyperthyroidism affects approximately 1.2% of the population in the US. Although it occurs in both men and women, it’s up to 10 times more likely in females.

You’re at higher risk for hyperthyroidism if you:

  • Have a family history of thyroid disease
  • Have pernicious anemia (a vitamin B12 deficiency)
  • Have type 1 diabetes
  • Have primary adrenal insufficiency, also known as Addison’s disease (a disorder where your adrenal glands don’t produce enough hormones, such as cortisol)
  • Consume an iodine-rich diet or medications containing iodine (like amiodarone)
  • Are over the age of 60
  • Were pregnant within the past 6 months
  • Had thyroid surgery or a thyroid problem such as a goiter also known as a swollen thyroid gland 

What are hyperthyroidism symptoms?

Though an overactive thyroid brings on a constellation of high thyroid symptoms (many related to weight and appetite), some of them don’t seem obviously linked to the condition (like increased anxiety and sweating). Here’s what to look for.

Common Symptoms of Hyperthyroidism Include:

  • Appetite Changes. While higher levels of TSH are reported to lead to a decrease in food intake, T3 has been shown to do just the opposite. So, depending on which hormone your thyroid gland decides to overproduce, you could find yourself hungry all the time or feel like you’re losing your interest in food altogether.
  • Insomnia. Since hyperthyroidism overstimulates the nervous system, this can make it difficult for you to get a quality night’s sleep. In addition to having a hard time falling asleep, you might also experience night sweats and wake up multiple times after you go to bed.
  • Emotional extremes. Anxiety, irritability, mood swings, and nervousness are some of the symptoms of emotional overactivity you might experience due to an overactive thyroid gland.
  • Fatigue or Muscle Weakness. As if hyperthyroidism didn’t already bring with it a ton of varied symptoms, some of its symptoms can also have their own sub-symptoms. For example, as a result of your nightly struggle to get the precious sleep your body needs, you may end up feeling tired or weak during the day.
  • Fertility and Menstruation Issues. High thyroid hormone levels can throw your other hormone levels out of whack, disrupting your ability to conceive. Prepubescent girls with hyperthyroidism might experience delayed menstruation, while menstruating women may experience decreased menstrual flow (hypomenorrhea) as well as missed periods (amenorrhea).
  • Frequent Bowel Movements. An overactive thyroid also meddles with most of your gastrointestinal tract, resulting in up to a quarter of patients making repeated visits to the bathroom and experiencing regular bouts of diarrhea.
  • Hand Tremors and Shakiness. If you’re noticing any erratic, involuntary movements in your hands or arms, it’s definitely a sign to get tested. Hyperthyroidism is linked to movement disorders and can even aggravate the tremors associated with the neurodegenerative disorder Parkinson’s disease if left to progress.
  • Heart Palpitations or Irregular Heartbeat. This is a big one. Your thyroid hormone directly affects your heart. So, when hyperthyroidism increases your heart rate, you can experience palpitations and abnormal heart rhythm, also known as atrial fibrillation. Needless to say, anything that puts your heart at risk should be taken seriously and addressed immediately.
  • Heat Intolerance and Excessive Sweating. Your thyroid gland regulates your body temperature. Well, guess what? When your thyroid gland makes more thyroid hormones than your body needs, your temperature is also likely to rise. As a result, you might find yourself extra sensitive to heat and perspiring 24/7.
  • Increased Blood Sugar. Thyroid disease has been linked to diabetes, and diabetic patients who develop hyperthyroidism have a higher risk of complications. Hyperthyroidism speeds up the rate that insulin is metabolized and increases the production and absorption of glucose. This can result in increased insulin resistance, which is extra problematic if you’re diabetic.
  • Skin, Hair, and Nail Problems. You might experience thinning hair and skin, redness in your face, elbows, and palms, Plummer’s nails (where the nail body separates from the nail bed), rashes and hives, or find yourself unexpectedly going gray at a young age.
  • Nausea and Vomiting. The link between these symptoms and an overactive thyroid has not been widely reported yet, but new research suggests that they can be major indicators of the condition.
  • Shortness of Breath. A number of respiratory issues can result from hyperthyroidism, including:
    • Dyspnea (difficult or labored breathing)
    • Hyperventilation (deeper and more rapid breathing)
    • Pulmonary arterial hypertension (high blood pressure in the blood vessel that carries blood from the heart to the lungs)
  • Sudden Paralysis. Known as thyrotoxic periodic paralysis, this relatively rare symptom involves severe muscle weakness and only occurs in people with high hormone levels. It predominantly affects Asian and Latinx men.
  • Swollen Base of Your Neck and Thyroid. Also called a goiter, an enlarged thyroid gland is usually painless but can cause a cough or, in more severe cases, make it difficult for you to swallow or breathe.
  • Weight Fluctuations. Hyperthyroidism is notoriously linked with weight loss, and for good reason: it kicks your metabolism into high gear, often making it difficult, if not impossible to put on weight—even with increased food intake. Although less common, it is also possible for your oversized appetite and resulting food intake to increase to a point where they overtake the increase in your metabolic rate, resulting in weight gain.

See more hyperthyroidism symptoms.

How is hyperthyroidism diagnosed?

Early detection is important so that you and your doctor can outline a plan for hyperthyroidism treatment before it causes irreversible damage. Dr. Brenessa Lindeman, Assistant Professor of Surgery and Medical Education at the University of Alabama at Birmingham, emphasizes the need for people with suspicious symptoms to advocate for your own health and get checked for hyperthyroidism early to prevent serious complications like osteoporosis, premature menopause, or even cardiac arrest.

Methods of diagnosis for hyperthyroidism include:

  • Analysis of medical history and symptoms
  • Physical examination
  • An ultrasound or nuclear medicine scan of your thyroid to see if it has nodules, or to determine whether it is inflamed or overactive
  • Blood tests to measure levels of thyroid hormones, including:
    • Thyroid stimulating hormone (TSH)
    • Thyroid hormone triiodothyronine (T3)
    • Thyroid hormone thyroxine (T4)
    • Thyroid peroxidase antibody (TPO)

Hyperthyroidism Treatment

  • Antithyroid Medications. These drugs interfere with the production of thyroid hormones. Methimazole (brand name Tapazole) is the most commonly prescribed hyperthyroidism medication, whereas propylthiouracil (also known as PTU) is preferred during the first trimester of pregnancy. Antithyroid drugs carry a small risk (0.2-0.5% of Graves’ disease patients) of agranulocytosis, which is a rare but serious blood condition that can result in death.

Dr. Debbie Chen, Clinical Lecturer and Research Fellow at the University of Michigan, recommends: “Patients treated with anti-thyroid medications such as methimazole or propylthiouracil should follow up regularly with their doctors to determine whether or not the dose needs to be adjusted based on their thyroid function test results. It’s also important for patients with Graves’ disease who go into remission to follow up with their doctors to monitor for the recurrence of hyperthyroidism.”

  • Radioactive Iodine (RAI) Therapy. This method damages the cells that make thyroid hormones. Historically, it’s been the preferred hyperthyroidism treatment method among US physicians, though recent trends are swinging the pendulum toward antithyroid medications. RAI therapy is recommended for those who are particularly vulnerable to antithyroid medication and surgery. While it’s widely considered safe and effective, a recent study found that RAI therapy is associated with a small but significant risk of death from solid cancer (abnormal cellular growth in an organ).
  • Surgery. Also known as a thyroidectomy, the surgery to remove the thyroid (either one part or the entire gland) can be an effective treatment for hyperthyroidism. Possible complications include hypocalcemia (low calcium in blood) and airway obstruction, though both occur in under 5% of surgeries.

Your choice of treament for your hyperactive thyroid will depend on the severity and underlying cause of your symptoms, your age, whether you’re pregnant, and any other individualized health factors.

In addition to these options, your doctor may also prescribe beta-blockers to minimize some of the effects of thyroid hormones on your body, such as to slow down a rapid heart rate and reduce hand tremors.

Where can I find support?

Hyperthyroidism impacts you physically, psychologically, and emotionally. It’s critical that you have a strong network of people you trust and can turn to for support.

It starts with your family. Since thyroid disease runs in families, being honest and open with your relatives is the best policy, as you might be alerting them to a problem they didn’t even know to look out for.

To help you build your own support network outside of those closest to you, check out the Graves’ Disease & Thyroid Foundation’s (GDATF) community resources to find a support group near you. If you don’t want to leave home, their online forum is another great resource for connecting and widening your net.

Hyperthyroidism Help

  • ThyroidChange. If you want to join a community that pushes for personalized care and support for patients with thyroid disease, look no further. You can also use their website to learn more about thyroid disease and its treatments, find a doctor based on specific criteria and patient recommendations, or schedule a telemedicine appointment with a doctor for your thyroid care.
  • The American Association of Endocrine Surgeons (AAES). Since finding a high-volume, experienced surgeon is critically important when choosing a thyroidectomy to treat your hyperthyroidism, this organization makes it easy with its Surgeon Finder tool.

What are the more serious complications of hyperthyroidism?

People with advanced and extreme hyperthyroidism face a ramshackle of problems, some of them life-threatening. The good news, though, is many patients do not reach this level of severity. Complications can include:

  • Graves’ ophthalmopathy or Thyroid Eye Disease (an eye condition causing double vision, light sensitivity, eye pain, and even vision loss), which may soon be treatable using a new drug called Teprotumumab
  • Irregular heartbeat, which can lead to:
    • blood clots
    • heart failure
    • stroke
    • other heart problems
  • Thyroid storm (a life-threatening condition resulting from a major stress such as trauma, heart attack, or infection)
  • Pregnancy complications
    • high blood pressure during pregnancy
    • low birth weight
    • miscarriage
    • premature birth
  • Thinning bones and osteoporosis

Bottom line: The longer you have an overactive thyroid and go without treatment, the greater the risk of lifelong complications, even after treatment. As over 60 percent of people with thyroid disease go undiagnosed, it’s important to listen to your body before reversible symptoms like weight loss and insomnia become life-threatening issues such as irregular heartbeat (arrythmia), bone loss (osteoporosis), and infertility (early menopause).

Do One Thing Right Now

Relax! Slowing things down is key—even if it feels counterintuitive with all the “sped up” effects of the condition. The GDATF recommends practicing yoga, Tai Chi, self-hypnosis, and meditation.

FAQ: Frequently Asked Questions

Is Graves’ disease the same as hyperthyroidism?

Graves’ disease is an autoimmune disorder that leads to and is the most common cause of hyperthyroidism, but they’re not the same thing. While all patients with Graves’ disease have hyperthyroidism, patients with hyperthyroidism may not necessarily have Graves’ disease (or non-Graves’ hyperthyroidism).

In Graves’ disease, the body makes an antibody (a protein produced to protect against a virus or bacteria) called thyroid-stimulating immunoglobulin (TSI), which causes the thyroid gland to make too much thyroid hormone (hyperthyroidism). Graves’ disease runs in families and is more commonly found in women.

Hypothyroidism vs Hyperthyroidism: What’s the difference?

The difference all comes down to the prefix in each word: hyper means over or exaggeration, while hypo means under or beneath. When it comes to -thyroidism, hyper- means an overactive thyroid gland, and hypo- means an underactive one.

Hypothyroidism, or an underactive thyroid gland, can actually be caused by treatments for hyperthyroidism, since their whole purpose is to decrease thyroid gland activity. Those treatments, however, can tip the balance too far.

What should I eat to manage hyperthyroidism?

With hyperthyroidism, it’s more important to manage what you don’t eat. High levels of iodine consumption can exacerbate hyperthyroidism, so it’s a good idea to watch your iodine intake. Look for ways to limit iodine in your diet by restricting your consumption of foods such as: fish, seaweed, shrimp, dairy products, and grain products (like cereal and bread).

Definitely check with your doctor before taking any medications or supplements with iodine. Sodium can also contribute to edema (swelling), which is common with Graves’ disease, so you’ll also want to watch your salt intake.

While there is no particular hyperthyroidism diet, there are foods which can give you a bit of a boost in your fight with hyperthyroidism. Since some symptoms can sap your energy, you should eat lots of fresh fruits and vegetables to get a steady supply of the vitamins and minerals your body needs. Berries are a smart choice because they’re high in antioxidants, while cruciferous veggies like broccoli, cauliflower, and cabbage have compounds called goitrogens that can actually decrease the thyroid hormone produced by your body.

Does hyperthyroidism go away on its own?

Not usually. Unfortunately, you can’t even do a whole lot on your own to rid yourself of the condition. If you want to minimize the many health risks posed by hyperthyroidism, the best thing you can do is ask to get tested by your doctor early if you are displaying symptoms. The sooner it’s detected, and a hyperthyroidism treatment plan is put into action, the better your chances are of successfully beating it.

Hyperthyroidism Fast Facts

  • Hyperthyroidism affects 1.2% of the U.S. population
  • Women are over 10 times more likely to have hyperthyroidism
  • Being over 60 puts you at a higher risk of developing hyperthyroidism
  • 6 months postpartum is a high-risk time for hyperthyroidism
  • Graves’ disease affects 1% of the U.S. population
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