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January 02, 2023 8 min read

Atrial fibrillation, or AFib, is one of the most common heart rhythm disorders and can have a huge impact on your life. But did you know that your thyroid health could be linked to the condition?

In this article, we'll explore the potential link between thyroid and atrial fibrillation, as well as symptoms you need to watch out for and how you can treat both effectively.

What is the thyroid?

The thyroid is a small gland located in the front of your neck, just below Adam's apple, under the skin. It's shaped like a butterfly with a smaller center and has two wide wings that cross over the side of your throat. It's part of the endocrine system and is the largest endocrine gland in your body. The main job of your thyroid gland is to create and secrete thyroid hormones. The main ones are thyroxine (also known as T4 because there are 4 iodine molecules in its composition) and triiodothyronine hormone (also known as T3). T4 is the inactive thyroid hormone. And it needs to be converted into T3 for your body to use it.

The thyroid hormones regulate your metabolism, which is the process of how your body turns food into energy. Since every cell in your body needs energy to function, the health of your thyroid gland can affect your entire body. The thyroid hormones also influence your blood pressure, cholesterol level, and heart rate.

What are the two most common thyroid problems?

There are two main types of thyroid disease: hypothyroidism and hyperthyroidism.

Hypothyroidism, or underactive thyroid, is a condition that occurs when your thyroid doesn't create and secrete enough hormones, causing your metabolism to slow down. This condition is common, affecting about 10 million people in the United States alone.

In contrast, hyperthyroidism occurs when your thyroid creates and secretes too much thyroid hormone, causing your metabolism to speed up. Also known as overactive thyroid, this condition is far less common than hypothyroidism. It affects approximately 1 out of 100 people over the age of 12 in the United States.

What is atrial fibrillation?

Atrial fibrillation, often called AFib or AF for short, is a heart condition that causes an irregular and often abnormally rapid heartbeat. It can lead to blood clots, heart failure, stroke, and other heart-related complications.

In atrial fibrillation, the upper chambers of the heart (the two atria) beat irregularly and out of sync with the lower chambers of the heart (the two ventricles). This affects blood flow from the atria to the ventricles. Atrial fibrillation can be a permanent condition or occur in brief episodes.

Atrial fibrillation can be caused by several factors, such as high blood pressure, sleep apnea, and heart disease. It can also be caused by thyroid problems.

How do thyroid problems cause atrial fibrillation?

The thyroid hormones help control your heart rate. Thus, having too low or too much thyroid hormone can affect the function of your heart in a number of ways.

When your thyroid is too active and produces too much of its hormones, everything speeds up. All those extra hormones are like a turbo boost to your metabolism and heart rate - everything is running faster than it should be. And that increased heartbeat can eventually lead to atrial fibrillation.

With hypothyroidism, everything slows down, including your heart rate. This means that it normally doesn't cause atrial fibrillation. But taking a high dose of thyroid hormone replacement medication might result in hyperthyroidism, which raises your risk of atrial fibrillation.

Do people who have thyroid problems always have atrial fibrillation?

You are at an increased risk for developing atrial fibrillation if you have hyperthyroidism, especially if you are over the age of 60. Atrial fibrillation is the most common heart condition in hyperthyroidism patients.

Moreover, research has shown that people with subclinical hyperthyroidism (a condition where you have slightly elevated thyroid hormone levels and low levels of thyroid-stimulating hormone (TSH) - a hormone produced by your pituitary gland that helps to regulate the production and release of thyroid hormone) have a higher incidence of atrial fibrillation compared to those with normal thyroid function. In fact, those with high normal thyroid function (slightly elevated thyroid hormone levels) have a 12% higher risk of developing atrial fibrillation. Those with subclinical hyperthyroidism, on the other hand, have a 30% higher risk of atrial fibrillation.

However, if you have atrial fibrillation and you've never had any thyroid disease before, an overactive thyroid is probably not the cause.

What are the symptoms you need to watch out for?

The symptoms of hyperthyroidism and atrial fibrillation are different. Here are the symptoms of each condition that you need to watch out for:

Symptoms of the overactive thyroid gland

Whether you have hyperthyroidism or you're taking too much thyroid hormone replacement medication, the symptoms are similar. You may experience the following if you have excess thyroid hormone:

  • Anxiety and nervousness

  • Mood changes

  • Sleeping trouble

  • Sensitivity to heat

  • Weakened muscles

  • A bulge in your neck

  • Erratic rapid heartbeat

  • Unexplained weight loss

  • Shakiness

  • Changes in your menstrual periods (for women).

Symptoms of atrial fibrillation

Some people with atrial fibrillation don't experience any symptoms, but others may experience the following:

  • Heart palpitations (sensations of a pounding heart)

  • Shortness of breath

  • Lightheadedness

  • Weakness

  • Chest pain

  • Dizziness

  • Fatigue

  • Decreased capacity for exercise

  • Breathing difficulty

  • Weakness

  • High blood pressure.

Keep in mind that having these signs and symptoms doesn't always mean you have thyroid problems or atrial fibrillation. But if you experience any of them, it's a good idea to see your doctor. They can help you find out for sure what's causing your symptoms.

How do doctors diagnose thyroid problems and AFib?

Here are some tests your doctor may order to diagnose thyroid problems and atrial fibrillation:

Thyroid tests

Your doctor may request one or more blood tests to diagnose thyroid dysfunction, such as the TSH test, T4 test, T3 test, and thyroid antibody tests. These tests involve a blood draw and blood pressure measurement, and the results will be analyzed in a lab. These tests may also help your doctor diagnose subclinical thyroid disease, such as subclinical hypothyroidism and subclinical hyperthyroidism.

The TSH test is usually the first test performed to assess thyroid function. If your TSH level is high, it may indicate hypothyroidism. On the other hand, low levels of TSH may indicate that you have hyperthyroidism. If your TSH test results are abnormal, you may need to take additional tests to determine the cause of the problem.

The T4 test measures the level of T4 in your blood. High levels of T4 may indicate hyperthyroidism, while low levels may indicate hypothyroidism. In some cases, however, T4 levels may be low or high without necessarily indicating a thyroid disorder. For example, T4 levels may be elevated during pregnancy or when you're using an oral contraceptive.

The T3 test is usually the last test performed. It's done to confirm the diagnosis if your doctor suspects you may have thyroid dysfunction even though your T4 level is normal. Measuring both T4 and T3 levels is especially helpful in making the diagnosis of hyperthyroidism since T4 might occasionally be normal even when T3 is high.

Atrial fibrillation tests

For atrial fibrillation, you might get the following tests:

1. Electrocardiogram

An electrocardiogram (ECG or EKG) is a quick and painless test to measure the electrical activity of your heart. During this test, electrodes (sticky patches) ate attached to your arms, legs, and chest. These electrodes are connected by wires to a computer that records the test results. An EKG can show your heart rate and is often used to diagnose conditions like new-onset atrial fibrillation.

2. Echocardiogram

An echocardiogram is a non-invasive test that uses sound waves to produce images of the size, structure, and movement of your heart.

3. Stress test

Also known as an exercise test, a stress test involves monitoring your heart while exercising on a treadmill or a stationary bike. This test can help identify problems with the heart during physical activity.

How to treat thyroid problems and atrial fibrillation?

If your atrial fibrillation is caused by hyperthyroidism, then your treatment goal should be getting the levels of your thyroid hormone back to normal. However, it's important to get your atrial fibrillation under control first since this condition increases your risk of having a stroke.

Treatment for atrial fibrillation

The length of time you've had AFib, your symptoms, how likely you are to have a stroke, independent risk factors, and your general health may affect your treatment. Overall, the goal of the treatment is to regulate your heart rate, normalize your heart's rhythm, and avoid blood clots that might cause a stroke.

Your doctor may prescribe medicines to control your heart rate. The first option is usually beta-blockers. However, you may take calcium channel blockers if you can't tolerate beta-blockers. If you also have heart failure, your doctor may prescribe Digoxin instead.

If you are more likely to have a stroke, you might also need to take drugs to lower your risk of a blood clot. These may include anticoagulants like warfarin, rivaroxaban, dabigatran, and apixaban.

Treatment for thyroid disease

Once you get treatment for your AFib, the next step is addressing your thyroid problem. Here's how hyperthyroidism is usually treated:

Anti-thyroid drugs

With hyperthyroidism, you'll need to take anti-thyroid drugs, which work by stopping your thyroid gland from producing excess thyroid hormone. But while these drugs can control your thyroid quickly, they shouldn't be used as a long-term solution. This is because they will become more ineffective over time and can cause serious side effects with continued use.

Radioactive Iodine

Since anti-thyroid drugs are only a short-term solution, you'll usually need to undergo thyroid ablation.

This treatment involves taking a pill of radioactive iodine. This pill destroys all or part of your thyroid gland. Thus, your thyroid won't be able to make enough thyroid hormone to support your bodily's function. As a result, you'll have hypothyroidism.

Thyroid hormone replacement after removal of the thyroid

After your thyroid gland is removed through thyroid ablation, you'll experience hypothyroidism symptoms because there's no way your body can produce thyroid hormones without the thyroid gland. This condition is often referred to as post-ablative hypothyroidism.

Treatment for post-ablative hypothyroidism involves thyroid hormone replacement medication. You need to take the medication once daily to restore and balance your thyroid hormone levels. This is a lifelong treatment, so you'll need to take the medication even when you no longer experience hypothyroidism symptoms.

The two most common thyroid hormone replacement medications are levothyroxine and natural desiccated thyroid (NDT). Levothyroxine, like Synthroid and Levothroid, is the synthetic form of the T4 thyroid hormone. It's the standard treatment that your doctor will likely prescribe. However, most hypothyroid patients prefer NDT because it offers better relief of symptoms.

NDT is made of dried pig thyroid glands. It consists of both T4 and T3 thyroid hormones, which is closer to what the human thyroid produces compared to synthetic versions. The most popular NDT is Armour Thyroid, but if for some reason your doctor won't prescribe it or you're allergic to its ingredients, there are various alternatives available.

One of the best alternatives is VitaliThy, an NDT supplement that is free from common allergens like lactose, gluten, egg, fish, shellfish, artificial coloring, and artificial flavor. Plus, it contains Thyroid (USP), just like Armour Thyroid. Best of all, this natural desiccated thyroid is available to buy online, so you can sit back and relax while waiting for it to arrive at your door.


Is there a link between thyroid and AFib (atrial fibrillation)?


How to treat atrial fibrillation due to hypothyroidism overtreatment?

If your atrial fibrillation is caused by hypothyroidism overtreatment, it's important to talk to your doctor. In most cases, they will adjust your thyroid hormone medication. They'll likely ask you to get a regular blood test to ensure that you're getting the optimal dose of the medication.

Conclusion: AFib and Thyroid disease

Your risk of atrial fibrillation is closely associated with your thyroid function. Therefore, it's important to manage your thyroid disease with an effective treatment plan to reduce the risk of complications from atrial fibrillation.

Wojciech Majda
Wojciech Majda

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