Can Thyroid Disease Cause Heart Issues?

One of the most important reasons to diagnose and treat thyroid disease is to prevent the cardiac conditions that can result from it.

Thyroid disease can worsen cardiac symptoms in people with heart disease and accelerate underlying cardiac problems. It can even produce new heart problems in people with otherwise healthy hearts.

This article explains what the thyroid gland does and how it affects the heart. It also covers the difference in symptoms and treatment between an underactive and an overactive thyroid.

What Is the Thyroid Gland?

By producing just the right amount of thyroid hormone, the thyroid gland helps regulate your body's metabolism—most importantly, how much oxygen and energy your body uses. Thyroid hormones affect nearly every organ in the body, from the way your heart beats to your cholesterol levels.

Too little thyroid hormone (a condition known as hypothyroidism) or too much thyroid hormone (called hyperthyroidism) can affect the heart in different ways:

• Hypothyroidism: Also known as underactive thyroid, hypothyroidism is when the thyroid does not produce enough thyroid hormone. Without enough thyroid hormone, your body's organs can start to weaken or slow down.
• Hyperthyroidism: Also known as overactive thyroid, hyperthyroidism is when the thyroid produces too much thyroid hormone. With too much thyroid hormone, many of your body's functions can start to speed up.

How Does Hypothyroidism Affect the Heart?

When there is not enough thyroid hormone, neither the heart nor the blood vessels can function normally. The reduced level of thyroid hormone causes the heart muscle to pump less vigorously and eventually become weak.

In addition, the heart muscle cannot fully relax after each heartbeat. This failure to relax can produce diastolic dysfunction, or stiffening of the heart's pumping chambers—a condition that can lead to heart failure.

Hypothyroidism also causes blood vessels to stiffen, which can lead to high blood pressure (hypertension).

Cardiac Symptoms

Cardiac symptoms can occur in anybody with hypothyroidism, but they are especially likely in people who already have underlying heart disease.

Common cardiac problems associated with hypothyroidism include:

• Swelling (edema): Edema can occur as a result of worsening heart failure. In addition, hypothyroidism itself can produce a type of edema called myxedema, which is caused by an accumulation of abnormal proteins and other molecules in the fluid that surrounds the body's cells.
• Heart arrhythmias: Hypothyroidism may also worsen the tendency for premature beats and irregular, quivering heartbeats (atrial fibrillation).
• Heart palpitations: Heart palpitations can feel like a fluttering, pounding, or skipping sensation that lasts for seconds to minutes or longer, and may occur when you are active or at rest. With hypothyroidism, your heart has more difficulty regulating its pace, which can result in seemingly random changes in its rhythm or the force with which it pumps.
• Heart failure (new or worsening): Hypothyroidism can cause heart failure for the first time in patients with relatively mild underlying heart disease.
• High diastolic blood pressure (diastolic hypertension): The arteries can grow stiff with hypothyroidism, which causes diastolic blood pressure to increase.
• Shortness of breath (dyspnea): Shortness of breath on exertion and poor exercise tolerance in hypothyroidism is usually due to weakness in the skeletal muscles. In people who also have heart disease, it may be due to worsening heart failure.
• Slow heart rate (bradycardia): Your heart rate is modulated by thyroid hormone. In people with hypothyroidism, the heart rate is typically 10 to 20 beats per minute slower than normal, especially in patients who also have heart disease.
• Worsening of coronary artery disease (CAD): The reduction in thyroid hormone can actually make angina (chest pain) less frequent. But the increase in LDL cholesterol ("bad cholesterol") and C-reactive protein (an inflammatory protein) seen with hypothyroidism may accelerate any underlying CAD.

Hypothyroidism Treatments

Physicians often prescribe Synthroid (levothyroxine) to treat an underactive thyroid.

Taken once a day, this replacement hormone mimics thyroxine, the hormone that the thyroid gland produces naturally.

Hypothyroidism is a lifelong condition; If you are prescribed thyroid medication, expect to stay on it for life.

How Does Hyperthyroidism Affect the Heart?

When there is too much thyroid hormone, the heart muscle must work harder. For a person with heart disease, having an overactive thyroid can take a big physical toll.

Excess thyroid hormone increases the force of contraction of the heart muscle and increases the amount of oxygen demanded by the heart. It also increases the heart rate. As a result, the work of the heart is greatly increased.

Hyperthyroidism may be present without producing the classic textbook symptoms. So if you have cardiac symptoms that cannot otherwise be readily explained, have your thyroid function measured. The sooner, the better.

Cardiac Symptoms

Cardiac symptoms can occur in anybody with hyperthyroidism but can be particularly dangerous in people with underlying heart disease.

Common symptoms include:

• Fast heart rate (tachycardia) and palpitations: Too much thyroid hormone will make your heart work harder and faster. As a result, many people with hyperthyroidism experience noticeably fast or irregular heart beats. This can happen while at rest or during physical activity.
• Heart arrhythmias: Particularly in patients with underlying heart disease, hyperthyroidism can also produce a host of other arrhythmias, such as premature ventricular complexes (PVCs), ventricular tachycardia, and especially atrial fibrillation.
• Heart failure: Hyperthyroidism itself can produce heart failure, but only rarely. On the other hand, if pre-existing heart disease is present, greater risk of heart failure with hyperthyroidism is common. This can be difficult to treat.
• High systolic blood pressure (systolic hypertension): The forceful cardiac contraction increases systolic blood pressure, or the pressure within blood vessels during cardiac contraction.
• Shortness of breath: Shortness of breath with exertion can be due to the skeletal muscle weakness associated with hyperthyroidism or to worsening heart failure.
• Worsening angina: Patients with coronary artery disease often experience a worsening of symptoms with hyperthyroidism. These can include an increase in angina or even a heart attack.

Hyperthyroidism can cause increased heart rate at rest.

Hyperthyroidism Treatments

Physicians often prescribe Tapazole (methimazole) or Propylthiouracil (PTU) to treat hyperthyroidism. It's important to remember that these treatments are not a cure.

If a tablet treatment is unsuccessful, surgery to remove all or part of the thyroid gland is an alternative. So is a radioactive iodine treatment to slow the production of thyroid hormones.

Who Is at Risk for Thyroid Problems?

You are more likely to get thyroid disease if you:

• Were born female
• Are white and age 60 or older
• Have obesity
• Smoke cigarettes
• Have a family history of thyroid conditions
• Have a history of diabetes, anemia, or rheumatoid arthritis
• Had radiation therapy therapy to the head or neck, especially as a child, to treat cancer

To help reduce your risk of thyroid disease:

• Ask for a thyroid collar before getting X-rays taken
• Use iodized salt in moderation
• Quit smoking
• Self-check your neck for lumps and swelling
• Limit your soy intake
• Consider a selenium dietary supplement
• See your healthcare provider regularly

How Are Heart Problems Diagnosed?

If you are having any symptoms that could suggest a heart problem, your healthcare provider may wish to run tests. The diagnostic process may involve a combination of blood tests, heart monitoring, and imaging tests.

Types of tests your provider may order include:

Cardiac imaging: Advanced imaging techniques, such as a coronary CT (computed tomography) scan, or cardiac MRI (magnetic resonance imaging), can provide detailed clues about how strong the heart pumps, how well the heart valve performs, whether there are blockages in the heart, and much more.

Angiogram: This imaging technique may involve an X-ray, MRA (magnetic resonance angiogram), or CTA (computed tomography angiography). Angiogram differs from other imaging techniques in that it also involves the injection of contrast dye into the blood to provide a detailed look at blood vessels and heart valves.

Blood tests: In certain instances, a damaged heart muscle will trigger the release of telltale substances into your blood. Measuring the level of these substances via blood testing can help your provider understand how damaged your heart is. Other blood tests can be done to measure levels of cholesterol and triglycerides, which may be indicative of heart disease.

Echocardiogram: An echocardiogram is a type of cardiac ultrasound, in which a provider passes a small probe over the heart to measure sound waves that create echoes. These echoes can tell your provider how well your heart muscles and valves are working.

Electrocardiogram: For this test, your provider will attach small, adhesive electrodes to your skin, typically on the chest, arms, and legs. The electrodes are hooked up to a monitor by lead wires, and allow your provider to measure and interpret the natural electrical impulses of the heart. The electrocardiogram can reveal how fast your heart pumps blood, the steadiness of its rhythm, and whether the blood is being circulated properly.

Holter monitor: You can think of a Holter monitor as a portable, wearable electrocardiogram. With this test, you will wear the monitor for 24 hours or longer in order to measure your heart's electrical activity while you are away from your provider's office. The Holter monitor will record the strength and timing of your heart's pulses, the heart's rhythm, and more.

How to Keep the Heart Healthy

To keep your heart healthy:

• Eat a healthy diet: A heart-healthy diet is packed with a variety of fruits and vegetables, whole grains, healthy proteins (especially plant proteins or lean, unprocessed meat), minimally processed foods, and little to no added sugars or salt.
• Exercise regularly: At minimum, you should try to burn as many calories as you consume. The American Heart Association recommends starting with a baseline of 150 minutes of moderately intense exercise per week, then increasing the amount and intensity of your physical activity to burn more calories.
• Live tobacco-free: If you use tobacco or nicotine products of any kind, it's important to quit. This includes saying no to smoking, vaping, or chewing tobacco or nicotine products. You should also steer clear of secondhand smoke as best as you can.
• Control cholesterol and high blood pressure: It's a good idea to have your cholesterol levels and blood pressure checked at least once per year, or more frequently if you have a history of high levels. If you have been prescribed medication to manage one or the other, stay on top of it, and ask your provider how else you can keep your condition under control.
• Drink alcohol only in moderation: Moderate drinking is defined as one drink per day for women, and up to two drinks per day for men. Drinking excessively can lead to high blood pressure, heart failure, obesity, stroke, and other issues that can harm the heart.
• Manage stress: Chronic stress hormones have been linked to high cholesterol, triglycerides, blood sugar, and blood pressure. Look for ways to decrease stress in your life. Get plenty of exercise, find a support group, see a counselor for depression or anxiety, try breathing techniques, or any other method that works for you.

Summary

The thyroid gland, a small, butterfly-shaped gland at the back of your throat, performs many vital functions. Thyroid disease—resulting in too little thyroid hormone (hypothyroidism) or too much (hyperthyroidism)—can, therefore, have several consequences.

Heart issues tops the list. Among them? Spikes in blood pressure, irregular heartbeats, slow or fast heart rate, heart failure, and more.

Managing thyroid disease can have far more benefit than just reducing symptoms like fatigue. That includes reducing your risk of some of these concerns. Be sure to get tested for thyroid disease if you exhibit any signs, or if you are experiencing new or worsening cardiac health problems.