Can Hyperthyroidism Cause Heart Palpitations?

Overview

Heart palpitations describe the feeling of racing, fluttering, or pounding heartbeat. It is possible to feel palpitations in the chest, throat, or neck.

Many medical conditions can cause heart palpitations. These include thyroid disorders, such as hyperthyroidism and hypothyroidism.

What is the thyroid?

The thyroid is a small, butterfly-shaped endocrine gland that produces and releases two thyroid hormones — triiodothyronine (T3) and thyroxine (T4). The production of these hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the pituitary gland.

Main anatomy and location

The thyroid gland is located in the base of the throat, between Adam’s apple and the collarbone. It is made up of two connected lobes found on either side of the windpipe. A healthy thyroid gland usually isn’t visible or felt by palpating the neck. 

What are the main functions of thyroid hormones?

Thyroid hormones, especially T3, affect many organs and help control many aspects of growth, development, and metabolism. For example, thyroid hormones help to regulate:

• Heart rate

• Body temperature

• Brain development

• Muscle contraction

• Skin and bone maintenance 

• Metabolic rate 

It’s essential for the thyroid to produce the right amount of thyroid hormones and to have a healthy level circulating through the bloodstream. Too many or too few hormones can have negative implications on health. 

How do thyroid hormones affect your heart?

There is a close link between the heart and thyroid hormones. Thyroid hormones have direct and important effects on the entire structure of the heart — including the heart muscle, the heart’s conduction system, and the broader cardiovascular system and blood vessels. For example, thyroid hormones impact heart rate and the force of the heartbeat. 

Thyroid hormones also have indirect functions on the heart through the autonomic nervous system and other systems that influence heart function. One way that thyroid hormones are thought to affect heart rate is by binding to thyroid hormone receptors in the heart’s muscle cells and other targets in the heart and cardiovascular system. 

Effects of thyroid hormone on cardiovascular hemodynamics

Cardiovascular hemodynamics describes how blood flows through the cardiovascular system. Thyroid hormones are important for cardiovascular hemodynamics and how the heart pumps blood around the body. These hormones influence:

• Resistance in the peripheral blood vessels

• Blood volume

• Resting heart rate

• How well the left ventricle contracts 

• Preload of the heart (how the heart muscle cells stretch right before a contraction) 

Thyroid hormone effects on blood pressure regulation

Thyroid hormones are important for blood pressure regulation. One way thyroid hormones help to regulate blood pressure is by influencing the main determinants of blood pressure, including cardiac output (the amount of blood the heart pumps each minute) and total peripheral resistance in the blood vessels. 

Thyroid hormones also affect kidney function, which is tied to blood pressure. 

Thyroid disease and pulmonary hypertension

Pulmonary hypertension is a type of high blood pressure that affects the right side of the heart and the pulmonary arteries (the blood vessels that supply the lungs with blood). 

Research has found that thyroid disorders, including both hypothyroidism and hyperthyroidism, are linked to pulmonary hypertension development. One study¹ found that 35% of people with hyperthyroidism had pulmonary hypertension. 

Blood pressure can increase in hypothyroidism because the heart works harder to pump more blood around the body. The arteries often become rigid, making it difficult for blood to flow through. Blood pressure can increase in hyperthyroidism because the force of the heart’s contractions increases. 

Effects of common thyroid disorders on the heart

Hypothyroidism and hyperthyroidism are the two main thyroid disorders. They can be caused by various factors, including autoimmune conditions, inflammation, and medications, among other causes. 

Thyroid disorders can worsen pre-existing heart disease or increase the risk of developing it. 

Hyperthyroidism and the heart

Hyperthyroidism occurs when the thyroid is overactive and produces excess thyroid hormones. Some effects that hyperthyroidism can have on the heart include the following:

• A faster heart rate (tachycardia) may be one effect. A fast heart rate is a very common symptom experienced by almost all people with hyperthyroidism.

• Abnormal heart rhythms (arrhythmia) or atrial fibrillation may occur. Abnormal heart rhythm is a key feature of hyperthyroidism in older adults. 

• Heart palpitations can occur at rest, especially upon physical exertion. 

• Chest pain (angina) happens when there is reduced blood flow to the heart muscle. 

• Increased cardiac output occurs when the heart pumps more blood each minute. 

• Peripheral edema can occur, which refers to swelling in the lower legs or hands. 

• Exercise intolerance can become an issue, as there is a reduced ability for the heart to maintain strenuous physical activity.

• Congestive heart failure occurs when the heart cannot pump blood to meet the demands of the body.

• Pulmonary high blood pressure (hypertension) can occur, which is usually systolic (the pressure on blood vessels when the heart beats).

• Cardiovascular mortality is another effect. One study² found that heart failure patients with abnormal thyroid function had a 60% higher mortality rate than those with normal thyroid function. 

• Subclinical hyperthyroidism, a mild form in which TSH levels are low, but thyroid hormones are normal, may also increase the risk of cardiovascular problems.

Hypothyroidism and the heart

Hypothyroidism is when the thyroid gland is underactive and doesn’t produce enough thyroid hormone. It has been suggested that the effects of hypothyroidism on the heart aren’t as severe as the effects of hyperthyroidism and the excessive release of thyroid hormones. 

Effects of hypothyroidism on the heart can include:

• Slower heart rate (bradycardia)

• Hypertension, which is usually mild and diastolic (the pressure on the artery walls when the heart relaxes in between each heartbeat)

• Reduced cardiac output (where the heart pumps less blood around the body each minute) 

• Pericardial effusions, which is when there is too much fluid in the sac surrounding the heart

• Swelling (edema), which typically occurs due to heart failure 

• Heart failure

• Reduced contractility of the heart 

• Worsening of coronary artery disease

• Increased systemic vascular resistance 

Subclinical hypothyroidism (where TSH levels are high, but thyroid hormone levels are normal) may also increase the risk of having cardiovascular-related complications of hypothyroidism. 

Main signs and symptoms

Heart palpitations can make a person feel like their heart is racing, pounding, irregular, fluttering, skipping, or adding extra beats. Episodes of heart palpitations can last from seconds to minutes and potentially even longer. They can occur during physical activity or while at rest. 

Hyperthyroidism can cause symptoms such as:

• Nervousness 

• Fatigue

• Intolerance to heat

• Difficulty sleeping

• Tremor 

• Rapid and irregular heartbeat

• Diarrhea or frequent bowel movements

• Weight loss, despite an increased appetite

• Enlarged thyroid gland (goiter) 

Prevalence

It’s estimated that around 20 million people³ in the United States have a form of thyroid disorder. Between 10%–25% of people with hyperthyroidism have atrial fibrillation, which often includes heart palpitations as a symptom. Atrial fibrillation is more common in males over 60.

Who is at risk?

The risk factors for atrial fibrillation in people with hyperthyroidism include:

• Age (older adults are more likely to develop atrial fibrillation)

• Ischemic heart disease

• Congestive heart failure

• Obesity

• Chronic kidney disease

• High levels of protein in the urine (proteinuria)

Some studies have suggested that males with hyperthyroidism are more likely to get atrial fibrillation, whereas other studies show that females are more likely.  

Diagnosis

What tests are used to diagnose hyperthyroidism and heart problems?

Early screening and diagnosis of a thyroid disorder is important to prevent complications from developing. 

Diagnosing hyperthyroidism

Hyperthyroidism is diagnosed with blood tests. 

In hyperthyroidism,

• Thyroid-stimulating hormone (TSH) is low.

• The thyroid hormones thyroxine (T4) and triiodothyronine (T3) are higher than normal. 

The cause of hyperthyroidism can be determined with numerous other tests, including:

Radioactive iodine uptake test

The thyroid uses iodine to produce thyroid hormones. Radioiodine is taken orally and can be traced within the body to determine whether the thyroid is absorbing too much or too little of it. The doctor can see the iodine itself through a thyroid scan. 

Thyroid ultrasound

The ultrasound uses sound waves to produce images of the thyroid. A thyroid ultrasound can show whether thyroid nodules (growths on the thyroid gland) may be causing the thyroid problems. 

Diagnosing heart problems

If heart palpitations or other heart problems are suspected as a complication of a thyroid disorder such as hyperthyroidism, your doctor can conduct several tests to determine if you have an abnormal heart rhythm. 

These tests include:

• Electrocardiogram (ECG): Measures the electrical activity of the heart

• Holter monitoring: Uses a small wearable device that records the heart's rhythm and can detect irregular heartbeats 

• Echocardiogram: A type of ultrasound that uses sound waves to produce moving images of the heart 

How to manage the risk to the heart?

The first step to managing the risk to your heart is to get a diagnosis of thyroid disorder as soon as possible. Proper treatment can reduce the risk of developing heart-related complications. Although heart palpitations can be harmless, you should see a doctor when you experience them for the first time. 

The doctor can examine and monitor the patient’s thyroid and heart with regular checkups. A doctor may refer a patient with hyperthyroidism and heart palpitations to an endocrinologist (a doctor specializing in hormones) or a cardiologist (a heart specialist) who can provide more support and recommend treatment options. 

Ways to keep the heart healthy

Lifestyle changes may not be enough to prevent someone with hyperthyroidism from experiencing heart palpitations. However, there may be some ways to reduce or limit them as much as possible and keep your heart healthy. These include:

• Limit caffeine and nicotine intake.

• Avoid smoking.

• Try to reduce stress and anxiety, perhaps through relaxation and breathing techniques, yoga, or meditation. 

• Take part in regular physical activity.

Treatment

The treatment a doctor recommends depends on the cause of the hyperthyroidism or hypothyroidism, as well as the patient’s age, coexisting health conditions, and any underlying risk factors for heart problems. Regardless of the cause, treatment is important. 

Treating the underlying thyroid disorder, whether it is hyperthyroidism or hypothyroidism, can resolve cardiovascular problems in most cases. Some studies have found that after treatment has begun, a normal heart rhythm can be achieved in 2–3 months. 

It’s important that the treatment plan is followed carefully — especially where medications are involved. 

When a patient has hypothyroidism

Treatments for hypothyroidism include:

Thyroid hormone replacement therapy

Levothyroxine (Synthroid) is the recommended thyroid hormone replacement for hypothyroidism. Levothyroxine replaces the T4 thyroid hormone, which the thyroid gland doesn’t produce enough in hypothyroidism. Taking levothyroxine helps to increase thyroid hormone levels in the blood.

Levothyroxine can improve heart and cardiovascular problems related to hypothyroidism, including hypertension, heart rate, and heart rate variability in exercise. Levothyroxine usually needs to be taken for life. 

When a patient has hyperthyroidism

Between 55%-75% of people with atrial fibrillation due to hyperthyroidism can achieve a normal heart rhythm 3–6 months after starting treatment for hyperthyroidism. 

Hyperthyroidism can be treated in several ways, including:

Antithyroid medications

Two commonly used antithyroid medications are methimazole (Tapazole) and propylthiouracil. Antithyroid medications prevent the thyroid gland from overproducing thyroid hormones. This helps to bring thyroid hormone levels back within a normal range. 

Beta blockers

Beta blockers help reduce some physical cardiovascular-related symptoms of hyperthyroidism, such as rapid heart rate, heart palpitations, atrial fibrillation, anxiety, and heat intolerance. However, beta blockers don’t have any effect on thyroid hormone levels. 

Radioactive iodine

Radioactive iodine is a treatment taken orally and absorbed by the thyroid gland. It treats hyperthyroidism by reducing the size of the thyroid gland. However, the risk of radioactive iodine treatment is that the thyroid can become underactive, leading to hypothyroidism. 

Thyroid surgery

Thyroid surgery, also known as a thyroidectomy, involves removing part or all of the thyroid gland. Thyroid surgery is a less common treatment for hyperthyroidism. It is mainly used in people who are unable to take radioactive iodine or who don’t have a response when they try antithyroid medications.

Surgery may also be used in people who have nodules that are or are at risk of becoming cancerous. After someone has thyroid surgery, they need to take thyroid replacement medication for life.

The lowdown

Heart palpitations are a potential complication of hypothyroidism and hyperthyroidism, the two main thyroid disorders. If you experience heart palpitations or any other potential symptoms of hyperthyroidism or hypothyroidism, see your doctor as soon as possible. 

They can conduct tests to determine the cause of the thyroid disorder or the heart palpitations and recommend the best course of treatment for your individual circumstances. 

People also ask:

What are the cardiac symptoms of hyperthyroidism?

Cardiac symptoms of hypertension may include a fast and strong heart rate, abnormal heart rhythm, chest pain, swelling in the lower legs and hands, and heart palpitations. 

Are palpitations a symptom of hyperthyroidism?

Heart palpitations are a possible symptom of hyperthyroidism. They can occur because thyroid problems such as hyperthyroidism are closely linked to the heart. 

What do thyroid palpitations feel like?

Heart palpitations generally cause someone to become suddenly aware of their heartbeat. The heart may feel like it’s skipping or adding in an extra beat, beating too quickly or slowly, or pounding in your chest. You may feel heart palpitations in the chest, throat, or neck, and they can occur while you’re at rest or during physical exertion. 

Can thyroid problems cause heart flutters?

Thyroid problems such as hyperthyroidism can cause heart problems that cause your heart to flutter or feel like it skips a beat. Heart flutters are another word for heart palpitations.