The Link Between Thyroid Disorders and Heart Conditions

Maybe your heart pounds quickly and loudly, your hands shake with tremors, you feel dizzy, and it's hard to catch your breath. You break out in a sweat, gripped by a sense of fear. Or maybe you feel your heart skipping beats, racing, fluttering, or pounding. You may not realize that what feels like a panic attack or heart palpitations can be symptoms of hyperthyroidism or autoimmune Graves' disease, both of which involve an overactive thyroid. Because your thyroid and your heart are so closely intertwined, having any sort of thyroid disease can result in heart symptoms.

Your thyroid and your heart are closely linked together and what affects one can affect the other. This means that when you have a suspected or diagnosed thyroid disease, you should also be assessed for heart disease. Conversely, if you have certain heart diseases such as atrial fibrillation, heart failure, or bradycardia (slowed heart rate), you should have your thyroid function checked.

Having a thyroid disorder increases your chances of developing heart disease. Studies show that for people with hypothyroidism, treatment with thyroid hormones helps reduce this risk. Initial research has also found that thyroid hormone replacement therapy may be helpful for people who have chronic heart failure and people who've had a heart attack.

Whether your thyroid is overactive (hyperthyroidism) or underactive (hypothyroidism), the way it's functioning impacts how your heart works, which can cause some of the symptoms mentioned above, as well as others.

Hyperthyroidism and Your Heart

Some patients are misdiagnosed as having panic disorder or heart problems when they're actually hyperthyroid. The body produces too much thyroid hormone, which causes the heart to work harder, creating symptoms such as:

• Increased heart rate, even when you're resting and especially after exertion
• Higher blood pressure
• Heart palpitations
• Increased cardiac output (the amount of blood the heart pumps through the body)
• Increased pulmonary artery pressure
• Chest pain
• Increased heart contractions

Once treated for their overactive thyroid, these people go on to be free of these symptoms. However, hyperthyroidism also increases your risk of developing heart conditions such as the following, which can independently lead to palpitations and feelings akin to panic attacks:

• Heart failure
• Atrial fibrillation (an irregular heartbeat)
• Pulmonary hypertension (high blood pressure in your heart and lungs)
• Angina (chest pain due to heart disease)

A toxic multinodular goiter may also cause sporadic periods of hyperthyroidism. In turn, these episodes can be a trigger for panic attacks or cause heart palpitations.

Hypothyroidism and Your Heart

In a form of hypothyroidism called Hashimoto’s disease, the up and down activity of the thyroid can sometimes cause excess thyroid hormone to be released erratically. This may lead to the heart symptoms listed above.

However, typically hypothyroidism doesn't cause most people to have heart symptoms because it actually creates less of a demand on your heart. When heart signs and symptoms do occur, they may include:

• Slower heart rate, called bradycardia
• Decreased systolic blood pressure
• Increased diastolic blood pressure
• Decreased cardiac output (the amount of blood the heart pumps through the body)
• Decreased heart contractions
• Slower pulse
• Shortness of breath after exertion
• Pericardial effusions (excess fluid around the heart)
• Non-pitting edema (swelling) of the hands and feet

A condition called dyslipidemia, which means the lipids (fats) in your blood are abnormal, is very common in people with hypothyroidism. Having dyslipidemia increases your risk of developing heart disease and/or having a heart attack.

Usually, most people who have hyperthyroidism will find that once they're properly treated—for example, with antithyroid medications, radioactive iodine, or surgery—their panic attack-like feelings and heart symptoms become a thing of the past. This goes if you have hypothyroidism too since thyroid hormone replacement therapy typically resolves any heart symptoms you may have and helps your heart function properly.

That said, oftentimes in addition to treating the actual thyroid disorder, a type of blood pressure medication called a beta blocker (Inderal (propranolol) or Tenormin (atenolol), for example) is also prescribed for people with hyperthyroidism to ease symptoms like a fast heart rate, palpitations, and nervousness.

If you've been treated for your thyroid and you're still experiencing these episodes of panic attack-like or heart symptoms, you'll need to see your practitioner to determine if your symptoms are actually caused by your thyroid disease or if something else is behind them. There are several possibilities that may be explored.

Mitral Valve Prolapse

A heart valve irregularity that's more common in thyroid patients, mitral valve prolapse can produce symptoms such as:

• A pounding, fast heartbeat
• Heart palpitations
• Panic attacks
• Dizziness
• Shortness of breath
• Fatigue
• Chest pain

This condition can be diagnosed by an echocardiogram, and there are treatments, including beta blockers, that can alleviate your symptoms.

TSH Level

Another factor to consider with your doctor is your thyroid-stimulating hormone (TSH) level. Once treated with radioactive iodine (RAI), antithyroid drugs, or surgery for hyperthyroidism, most people become hypothyroid and are placed on thyroid hormone replacement.

But if you're on too high a dosage of thyroid hormone replacement and your TSH is at the lower end of the normal range, you may be borderline hyperthyroid due to overmedication. In this case, it's worth discussing a slight reduction in your dosage with your doctor to see if that alleviates your symptoms.

Similarly, if you're having periods of hyperthyroidism due to Hashimoto’s disease or toxic nodules, better treatment for your condition may resolve your panic and heart symptoms.

Mental Health Disorder or Heart Problem

If you and your doctor cannot determine any thyroid-related reasons for your symptoms, you may, in fact, have a panic or anxiety disorder, or some sort of heart irregularity. In these instances, you should be further evaluated by a heart specialist and/or a psychiatrist.

Besides heart problems or an anxiety disorder, other causes of panic attacks include:

• Drug use (stimulants such as caffeine, cocaine, or amphetamines)
• Hypoglycemia (low blood sugar)
• Medication withdrawal
• Adrenal gland issues, including pheochromocytoma

A Word From Verywell

With proper treatment of your thyroid disease, and possibly adding a beta blocker, your heart palpitations and panic attack symptoms should be alleviated. If not, talk to your doctor. You may need to be evaluated for other causes. Try to be patient through this process. With close follow-up and a thoroughly devised treatment plan, you can feel better.