Possible Complications Of Hyperthyroidism

If you think you have an overactive thyroid or you have recently been diagnosed with hyperthyroidism, you might be concerned about developing complications.

Hyperthyroidism can cause serious, potentially life-threatening complications if the condition is not properly treated. Knowing what symptoms to look out for and when to speak to a doctor is key to help you avoid health problems and ease side effects. Once diagnosed, your doctor can discuss treatment options that will help return your thyroid activity to normal.

Have you considered clinical trials for Hyperthyroidism?

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 does the thyroid do?

The thyroid is responsible for regulating the rate at which your body burns energy to keep you alive. This is called the basal metabolic rate (BMR). When your body needs more energy, your thyroid will speed up your metabolism by releasing the thyroid hormones T3 (triiodothyronine) and T4 (thyroxine).

The thyroid doesn't decide when your body needs more energy; instead, it works in conjunction with the pituitary gland. When your body needs a faster metabolism, the pituitary gland produces a hormone called thyroid-stimulating hormone (TSH) which tells your thyroid gland to produce more T3 and T4 hormones. This causes your cell activity to increase, elevating your body temperature and heart rate, and speeding up the conversion of food to energy.

What is hyperthyroidism?

When functioning correctly, your thyroid produces the exact amount of T3 and T4 hormones that your body needs to work. This delicate balance can be disturbed which might cause your thyroid to produce too much, or too little, hormone.

Hyperthyroidism, also called overactive thyroid, occurs when your thyroid gland produces more T3 and T4 than your body needs. This means your body has a permanently elevated metabolic rate which can cause side effects and serious complications without treatment.

Hyperthyroidism symptoms

Hyperthyroidism symptoms can vary from one person to the next.  Keep in mind that not every person with hyperthyroidism experiences every symptom. It’s also possible that older patients may experience different symptoms from younger people, such as lack of appetite instead of increased appetite.

Common hyperthyroidism symptoms include:

  • Enlarged thyroid, also known as a goiter

  • Increased appetite

  • Unexpected weight loss

  • Reduced heat tolerance

  • Rapid or irregular heart rate

  • Muscle weakness or shakiness

  • Increased frequency of bowel movements

  • Nervousness or irritability

  • Difficulty sleeping

  • Fatigue

Common hyperthyroidism complications

Hyperthyroidism can lead to complications that vary in severity. They cause their own set of symptoms and require specific treatments, so bear these in mind and know when it’s time to seek medical help.

If you are experiencing symptoms of hyperthyroidism complications but have not been diagnosed, speak to a doctor as soon as possible. This will allow for early diagnosis and treatment to help minimize your risk of serious health problems.

Graves’ eye disease

Although there are different potential causes and risk factors for hyperthyroidism, the most common cause is an autoimmune disorder called Graves’ disease. The disorder causes antibodies in the immune system to attack the thyroid, resulting in the overproduction of hormones.

These antibodies can attack other parts of the body as well. When they attack the eyes, it causes a condition called Graves’ eye disease (also called Graves’ orbitopathy or Graves’ ophthalmology) which can result in dry, irritated eyes. People with this condition may notice their eyes bulging or their eyelids swelling which can make it challenging to close the eyes. Graves’ eye disease can lead to various sight problems, including double vision, light sensitivity, and vision loss.

Graves’ dermopathy and acropachy

Graves’ dermopathy, a rare complication of Graves’ disease, causes the skin to thicken and redden. The condition usually affects the shins and the tops of the feet and causes them to take on a texture similar to an orange peel.

Acropachy is another rare complication of Graves’ disease that is similar to Graves’ dermopathy and causes the fingers and toes to thicken and appear clubbed.

Underactive thyroid (hypothyroidism)

Having an overactive thyroid can, surprisingly, lead to an underactive thyroid (hypothyroidism).

Most hyperthyroidism treatments work by slowing the function of the thyroid gland so it produces less hormone. This can cause hormone production in the thyroid to drop below normal levels, resulting in hypothyroidism.

Hypothyroidism is easily treated with hormone replacement therapy (levothyroxine), which should help your hormone levels return to normal.

Thyroid storm

Hyperthyroidism causes your metabolism to speed up as your thyroid produces too much T3 and T4 hormones; however, this isn't usually life-threatening. In rare cases, the metabolism speeds up too much and causes a serious medical condition called thyroid storm.¹

Common thyroid storm symptoms include:

  • High temperature

  • Rapid heart rate

  • Vomiting or diarrhea

  • Yellowing of the skin and eyes

  • Confusion

  • Loss of consciousness

If you have any symptoms of thyroid storm, seek emergency medical attention straight away.


Your bones are constantly breaking down and being replaced, and this should happen in equal proportion.

The thyroid plays an important role in regulating bone metabolism,² and hyperthyroidism can speed up bone turnover (the process of bone breakdown followed by new bone formation) and a shortened remodeling time, causing overall bone loss.

This results in brittle bones that break easily — a condition known as osteoporosis.

Often, osteoporosis is only diagnosed when a brittle bone breaks, so it is sometimes called the “silent disease”. The condition can be treated with medication that helps slow bone loss or speeds up the formation of new bone.

Your doctor may also recommend lifestyle strategies to treat osteoporosis, like changing your diet and exercise routine.

Pregnancy problems

Women with untreated or insufficiently treated hyperthyroidism have more risk of pregnancy complications, including miscarriage, premature labor, and low birth weight.

They may also be more likely to develop a condition known as preeclampsia, which is characterized by persistent high blood pressure during pregnancy and post-partum.

In rare cases, hyperthyroidism can be brought on by pregnancy. If you experience hyperthyroidism symptoms while pregnant, speak to your doctor as soon as possible.

Atrial fibrillation and stroke

The heart has two upper chambers and two lower chambers that work in unison during a normal heartbeat.

Hyperthyroidism can throw the heart’s rhythms out of sync, causing a condition called atrial fibrillation. This improper balance in the heart causes an irregular heartbeat that can be too fast or too slow.

Atrial fibrillation is a serious and potentially life-threatening condition that increases your risk of stroke. When the heart beats irregularly, it becomes less effective at pumping out blood which causes it to pool. Pooled blood can cause clots that make their way to the brain and cause a stroke.

Blood-thinning medication that reduces clotting can lower the risk of stroke, and other medications can also be used to help regulate your heartbeat.

Other heart problems

Hyperthyroidism also increases your chance of developing other heart problems,³ including hypertension (high blood pressure).

Excess thyroid hormone causes the heart to pump faster and harder, which elevates your blood pressure and puts you at risk of developing cardiovascular problems and organ damage.

Hyperthyroidism treatment

Treating hyperthyroidism involves taking steps to reduce the amount of hormone your thyroid produces.

Your doctor will discuss treatment options with you and select one based on the severity of your condition and other medical factors that may play a role.


Some medications can be used to inhibit the production of thyroid hormones. These include propylthiouracil and methimazole.

Radioactive iodine therapy

The thyroid works by converting iodine from the blood into thyroid hormones. When a doctor gives you radioactive iodine, your thyroid will absorb it and shrink. The substance is either injected or taken orally.


In some cases, your doctor may recommend a thyroidectomy to remove part or all of the thyroid gland. You may need to take hormone replacement therapy after surgery to ensure your body has enough hormones to function properly.

The lowdown

An overactive thyroid that produces more T3 and T4 hormones than the body needs speeds up your metabolism too much and affects how the body functions.

Some hyperthyroidism symptoms are mild, but untreated hyperthyroidism can cause you to develop several life-threatening conditions like thyroid storm and atrial fibrillation.

If you have hyperthyroidism symptoms, speak to your doctor as soon as possible to get a diagnosis. Your doctor can provide a treatment plan to help stabilize your thyroid and return your hormone levels to normal.

Have you considered clinical trials for Hyperthyroidism?

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.

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