What Are The Symptoms Of Hyperthyroidism?

Your thyroid gland is located in the front of your neck, just below your Adam's apple if you are male. It wraps around your windpipe and, in adults, a normal thyroid gland measures about two inches across. The shape of this gland is often compared to a bowtie or a butterfly.

Your thyroid gland plays an important role in your body's functions by producing two hormones:

  • Thyroxine (also called tetraiodothyronine), commonly referred to as "T4"

  • Triiodothyronine, often referred to as "T3"

These hormones control how your body uses energy, which in turn affects almost every organ in your body. If you have hyperthyroidism, your thyroid is overactive and produces too much of these hormones. This imbalance can cause a number of symptoms.

An overactive thyroid is not a contagious health condition. You can't catch hyperthyroidism or give it to someone else.

Hyperthyroidism is often hereditary. You may be at an increased risk if you have a close blood relative with hyperthyroidism.

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We make it easy for you to participate in a clinical trial for Hyperthyroidism, and get access to the latest treatments not yet widely available - and be a part of finding a cure.

What causes hyperthyroidism?

In the US, an autoimmune disorder called Graves' disease causes the majority of hyperthyroidism cases. Your immune system keeps you healthy by attacking germs and other foreign cells when it’s working properly. If you have an autoimmune disorder, your immune system mistakenly attacks your body's own healthy cells.

In Graves' disease, the immune system attacks the thyroid gland and causes it to overproduce hormones. According to the National Institute of Health (NIH), about 80% of people with hyperthyroidism have Graves' disease.¹

The exact cause of Graves' disease is unknown. If you have a family history or carry the genes for this autoimmune disorder, it's possible that a virus or some type of environmental exposure can trigger Graves' disease.

What are the symptoms of hyperthyroidism?

Your thyroid gland plays an important role in many of your body's functions. An overactive thyroid can cause changes that affect your entire body and your mood. Below is a list of some of the most common symptoms of hyperthyroidism:

Unexplained weight loss 

It's common for people with undiagnosed hyperthyroidism to lose weight without trying. If you don't weigh yourself on a regular basis, you may notice that your clothes are baggier. This weight loss happens even though your food and beverage intake is the same and without increased physical activity.

Increased appetite

An overactive thyroid can increase your metabolism. You may notice that you are more hungry than usual or need to eat more often. But despite eating more, you don't gain weight or even lose weight.

Hot flashes 

A hot flash occurs when you suddenly feel warm for no apparent reason. You may be sweating and fanning yourself, yet others around you do not feel hot. While hot flashes are often associated with menopause in women, hyperthyroidism hot flashes can affect both men and women of any age.

Heat intolerance

Oversensitivity to heat is different from a hot flash in that the air or room temperature is, in fact, warm. However, you may sweat and feel much more uncomfortable than usual.

Increased sweating 

People with hyperthyroidism may sweat more than usual. Increased sweating can happen even when you are not experiencing a hot flash or heat intolerance. You may find that you sweat through your shirt and clothing. If you use antiperspirant, it may not be as effective or even stop working.

Menstrual cycle changes

Women may notice that their periods are lighter, and that they do not bleed as much or for as long. Women with hyperthyroidism also may get their periods less frequently. Undiagnosed hyperthyroidism may cause difficulties in becoming pregnant. Some women see their doctor for infertility, only to discover that they have hyperthyroidism

Mood changes

Hyperthyroidism can bring on feelings of anxiety, irritability, and nervousness. While we all experience these emotions from time to time, untreated thyroid issues can make these feelings more pronounced. This may be a symptom that others around you notice.

Skin changes

A rarer side effect of Graves' disease is a skin condition called Graves' dermopathy or pretibial myxedema. Graves' dermopathy causes the skin on your shin or the top of your feet to thicken and become red. You may also notice that the affected skin has a rough texture.

Bulging eyes

Exophthalmos is the medical term for eyes that appear to bulge out of the sockets

Increased bowel movements

An overactive thyroid can make you have more bowel movements than usual. You may also experience unexplained diarrhea or loose stools.

Changes in heart rate

There may be times when you notice that your heart beats rapidly. Some people describe this as feeling as if their heart is "pounding" in their chest. Hyperthyroidism can also cause you to have an irregular heartbeat.

Difficulty sleeping

An overactive thyroid can make it difficult to get a good night's sleep. You may have trouble falling asleep or staying asleep. Increased sweating during the night or hot flashes can cause you to wake up.

Hyperthyroidism affects everyone differently. If you have hyperthyroidism, you may experience all or just a few of these symptoms.

How is hyperthyroidism different from hypothyroidism?

Hyperthyroidism should not be confused with another thyroid disorder, hypothyroidism. Although the words sound similar, these are two different conditions.

  • In medical terms, the prefix "hyper-" means "above normal” 

  • And the prefix "hypo-" means "below normal"

In hyperthyroidism, the body produces and releases too much thyroid hormone. If you are diagnosed with hyperthyroidism, you may be told that you have an overactive thyroid.

In hypothyroidism, the opposite is true. The body does not produce or release enough thyroid hormone. Some medical professionals may refer to hypothyroidism as having an underactive thyroid.

How is an overactive thyroid diagnosed?

Only a doctor can diagnose hyperthyroidism. If you have symptoms, your healthcare provider will take several steps to assess your symptoms and screen you for any thyroid conditions. You may have multiple doctor visits before a hyperthyroidism diagnosis is confirmed.

Physical exam

If you have symptoms of an overactive thyroid, your doctor will first perform a physical exam. They may check and record your vital signs such as your temperature, heart rate, and blood pressure. And, they may look at your skin for signs of Graves' dermopathy and other changes.

Medical and family history

Your doctor will also ask you about any hyperthyroidism risk factors that you have, such as a family history of thyroid disorders. Before your appointment, ask your parents and siblings if they have ever been diagnosed with a thyroid condition or an autoimmune disorder. If you don't know your family history, be honest with your doctor.

Blood tests

The symptoms of hyperthyroidism overlap with many other health conditions. A doctor typically cannot confirm a hyperthyroidism diagnosis without blood tests. These blood tests measure your:

  • T3 and T4 levels, which are the hormones produced by your thyroid gland

  • TSH level, a hormone produced by your pituitary gland (TSH tells your thyroid how much T3 and T4 to make)

  • Thyroid antibodies are present if you have an autoimmune disorder like Graves' disease

Your doctor may be able to diagnose your condition after a blood test. In some cases, you may need to have other diagnostic tests like an ultrasound, thyroid scan, or thyroid uptake test.


Your doctor may order an ultrasound to check for or take a closer look at any lumps on your thyroid, which are called nodules.

Thyroid scan

Prior to a thyroid scan, you will be given a small amount of radioactive iodine, either through an injection or in liquid or capsule form. After your body has time to absorb the iodine, a special camera will take photos of your thyroid. If you have hyperthyroidism, the radioactive iodine will be visible in the images.

Thyroid uptake test

In a thyroid uptake test, you will swallow radioactive iodine in liquid or capsule form. Then, a device called a gamma probe will be placed near your neck. The gamma probe measures how much of the iodine your thyroid takes up from your blood.

What are the risk factors for hyperthyroidism?

Women are five to eight times more likely to develop a thyroid condition² than men. Women who have had a recent pregnancy or just experienced menopause are at an increased risk.

Other risk factors for an overactive thyroid include:

  • Being older than 60 years of age

  • A family history of thyroid disease

  • Smoking cigarettes or using other nicotine products

  • Having pernicious anemia, type 1 or type 2 diabetes, or primary adrenal insufficiency

  • An increased iodine intake due to diet or certain medications

These risk factors may increase the likelihood that you will develop hyperthyroidism at some point in your life. However, having one or even multiple risk factors does not guarantee that you will ever develop the condition.

Is hyperthyroidism preventable?

No, hyperthyroidism is generally not considered to be a preventable health condition. Many of the risk factors for hyperthyroidism are out of your control, such as your sex, age, and family history.

You can reduce your chances of developing hyperthyroidism by not using nicotine products.

While certain prescription drugs contain iodine, you should not stop taking any medications without consulting with your doctor. The benefits of the drug may outweigh your risk of developing hyperthyroidism.

If you have several risk factors for an overactive thyroid, ask your doctor if routine screening is appropriate. The earlier you catch most medical conditions, the easier they are to manage.

What does the management and treatment of hyperthyroidism involve?

There are several ways to manage hyperthyroidism, but only certain treatments may be suitable for you. The treatment that your doctor recommends will be based on:

  • The cause of your hyperthyroidism, if known 

  • If you are pregnant or breastfeeding or plan to become pregnant soon

  • Your age

  • Your overall health

The most common ways to manage hyperthyroidism are prescription medications, radioactive iodine, and surgery.

Hyperthyroidism prescription medications 

If you are diagnosed with hyperthyroidism, your doctor may prescribe antithyroid medications. These prescription drugs prevent your thyroid from producing hormones. In the US, two common hyperthyroid medications are methimazole and propylthiouracil.

Radioactive iodine treatment for an overactive thyroid 

Your doctor may recommend radioactive iodine treatment, which is an oral medication. Over the course of a few weeks, the radioactive iodine destroys your overactive thyroid cells. If you choose this treatment, you will most likely have to take medication to maintain healthy thyroid hormone levels for the rest of your life.

While small amounts of radioactive iodine are used in some diagnostic tests, radioactive iodine treatment uses a different amount.

Surgery for hyperthyroidism

Your doctor may recommend a thyroidectomy, which is a surgery that removes all or part of your thyroid. Thyroidectomies are performed in a hospital under general anesthesia. If you have thyroid surgery, you may have to stay in the hospital for at least one night.

When to speak to a healthcare professional

If you have a family history of thyroid problems or you have several risk factors, tell your doctor. They will let you know if hyperthyroidism screening is available and appropriate.

You should make an appointment with your healthcare provider if you experience any symptoms of hyperthyroidism. If left untreated, an overactive thyroid can lead to heart issues, eye problems, and osteoporosis.

If you are diagnosed with hyperthyroidism, you may continue to have regular doctor and lab appointments. These appointments give your healthcare provider an opportunity to check your thyroid hormones and ensure that your treatment is working.

If you experience breakthrough symptoms after a diagnosis, make an appointment to see your doctor right away. Your medication may need to be increased or changed

The lowdown

Hyperthyroidism is not a contagious condition, but it can be hereditary. Anyone can develop an overactive thyroid, but women have a higher probability of doing so. The risk of developing hyperthyroidism increases with age, after a pregnancy, and after menopause.

Only a healthcare provider can diagnose the condition with additional tests. There are several treatments available to manage an overactive thyroid.

  1. Graves’ disease | (NIDDK) National Institute of Diabetes and Digestive and Kidney Diseases

  2. General information/Press room | American Thyroid Association


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