Hyperthyroidism, also called overactive thyroid, is when the thyroid gland makes more thyroid hormones than your body needs. The thyroid is a small, butterfly-shaped gland in the front of your neck. Thyroid hormones control the way the body uses energy, so they affect nearly every organ in your body, even the way your heart beats.
If left untreated, hyperthyroidism can cause serious problems with the heart, bones, muscles, menstrual cycle, and fertility. During pregnancy, untreated hyperthyroidism can lead to health problems for the mother and baby.
Thyroid hormones control your:
- heart rate
- nervous system
- body temperature
When your thyroid gland is overactive, your body’s processes speed up. This acceleration can bring about:
- rapid heartbeat
- hand tremors
- excessive sweating
- weight loss
- difficulty sleeping
How common is hyperthyroidism?
About 1.2 percent of people in the United States have hyperthyroidism.1 That’s a little more than 1 person out of 100.
Who is more likely to develop hyperthyroidism?
Women are 2 to 10 times more likely than men to develop hyperthyroidism.2 You are more likely to have hyperthyroidism if you
- have a family history of thyroid disease
- have other health problems, including
- pernicious anemia NIH external link, a condition caused by a vitamin B12 deficiency
- type 1 diabetes
- primary adrenal insufficiency, a hormonal disorder
- eat large amounts of food containing iodine NIH external link, such as kelp, or use medicines that contain iodine, such as amiodarone NIH external link, a heart medicine
- are older than age 60, especially if you are a woman
- were pregnant within the past 6 months
What causes hyperthyroidism?
- 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?
In the US, hyperthyroidism affects approximately 1.2% of the population. Although it occurs in both men and women, it’s up to 10 times more likely in women.
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 a.k.a. a swollen thyroid gland
What are the symptoms of hyperthyroidism?
Though hyperthyroidism brings on a constellation of 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 hyperthyroidism symptoms 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 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. Hyperthyroidism 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, stat. 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 hyperthyroidism 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.
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)
What are my hyperthyroidism treatment options?
You may receive medicines, radioiodine therapy, or thyroid surgery to treat your hyperthyroidism. The aim of treatment is to bring thyroid hormone levels back to normal to prevent long-term health problems and to relieve uncomfortable symptoms. No single treatment works for everyone.
Treatment depends on the cause of your hyperthyroidism and how severe it is. When recommending a treatment, your doctor will consider your age, possible allergies to or side effects of the medicines, other conditions such as pregnancy or heart disease, and whether you have access to an experienced thyroid surgeon.
Beta blockers. Beta blockers do not stop thyroid hormone production, but can reduce symptoms until other treatments take effect. Beta blockers act quickly to relieve many of the symptoms of hyperthyroidism, such as tremors, rapid heartbeat, and nervousness. Most people feel better within hours of taking beta blockers.
Antithyroid medicines. Antithyroid therapy is the simplest way to treat hyperthyroidism. Antithyroid medicines cause the thyroid to make less thyroid hormone. These medicines usually don’t provide a permanent cure. Health care providers most often use the antithyroid medicine methimazole. Health care providers more often treat pregnant women with propylthiouracil during the first 3 months of pregnancy, however, because methimazole can harm the fetus, although this happens rarely.
Once treatment with antithyroid medicine begins, your thyroid hormone levels may not move into the normal range for several weeks or months. The total average treatment time is about 1 to 2 years, but treatment can continue for many years. Antithyroid medicines are not used to treat hyperthyroidism caused by thyroiditis.
Antithyroid medicines can cause side effects in some people, including
- allergic reactions such as rashes and itching
- a decrease in the number of white blood cells in your body, which can lower resistance to infection
- liver failure, in rare cases
Call your doctor right away if you have any of the following symptoms:
- dull pain in your abdomen
- loss of appetite
- skin rash or itching
- easy bruising
- yellowing of your skin or whites of your eyes, called jaundice
- constant sore throat
Doctors usually treat pregnant and breastfeeding women with antithyroid medicine, since this treatment may be safer for the baby than other treatments.
Radioactive iodine is a common and effective treatment for hyperthyroidism. In radioiodine therapy, you take radioactive iodine-131 by mouth as a capsule or liquid. The radioactive iodine slowly destroys the cells of the thyroid gland that produce thyroid hormone. Radioactive iodine does not affect other body tissues.
You may need more than one radioiodine treatment to bring your thyroid hormone levels into the normal range. In the meantime, treatment with beta blockers can control your symptoms.
Almost everyone who has radioactive iodine treatment later develops hypothyroidism because the thyroid hormone-producing cells have been destroyed. However, hypothyroidism is easier to treat and causes fewer long-term health problems than hyperthyroidism. People with hypothyroidism can completely control the condition with daily thyroid hormone medicine.
Doctors don’t use radioiodine therapy in pregnant women or in women who are breastfeeding. Radioactive iodine can harm the fetus’ thyroid and can be passed from mother to child in breast milk.
The least-used treatment for hyperthyroidism is surgery to remove part or most of the thyroid gland. Sometimes doctors use surgery to treat people with large goiters or pregnant women who cannot take antithyroid medicines.
Before surgery, your doctor may prescribe antithyroid medicines to bring your thyroid hormone levels into the normal range. This treatment prevents a condition called thyroid storm—a sudden, severe worsening of symptoms—that can occur when people with hyperthyroidism have general anesthesia NIH external link.
When part of your thyroid is removed, your thyroid hormone levels may return to normal. You may still develop hypothyroidism after surgery and need to take thyroid hormone medicine. If your whole thyroid is removed, you will need to take thyroid hormone medicine for life. After surgery, your doctor will continue to check your thyroid hormone levels.
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 a.k.a. 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
- 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
- premature birth
- Thinning bones and osteoporosis
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.
People with Graves’ disease or other type of autoimmune thyroid disorder may be sensitive to harmful side effects from iodine. Eating foods that have large amounts of iodine—such as kelp, dulse, or other kinds of seaweed—may cause or worsen hyperthyroidism. Taking iodine supplements can have the same effect. Talk with members of your health care team about what foods you should limit or avoid, and let them know if you take iodine supplements. Also, share information about any cough syrups or multivitamins that you take because they may contain iodine.