The Link Between Thyroid Disorders and Heart Conditions

Hyperthyroidism is caused by the overproduction of thyroid hormones by the thyroid gland, a butterfly-shaped organ at the base of the neck.

The shortness of breath, racing heart, and related symptoms may be confused with a panic attack or heart palpitations. However, these symptoms—and others caused by hypothyroidism, or low thyroid function—can occur because your thyroid and heart function are closely linked.

This article explains the connection between your heart and your thyroid. It discusses possible causes of these symptoms, the thyroid levels that may lead to them, and some treatment options.

Thyroid and Heart Symptoms

The thyroid has at least some effect on every organ in the body, including the heart. Your thyroid impacts your heart function in different ways because of its influence.

This is true whether it is underactive, as in hypothyroidism, or in the overactive state of hyperthyroidism. It's also why the thyroid can be the cause of symptoms that seem like a panic attack, such as chest pain, but that require a different diagnosis and treatment.

Hyperthyroidism and Your Heart

Some people may be misdiagnosed as having panic disorder or heart problems. In reality, they may actually have an overactive thyroid. The body makes too much thyroid hormone, which causes the heart to work harder.

Thyroid hormone levels that are too high cause increases in the heart rate, the force of heart muscle contraction, and the amount of oxygen the heart needs. As a result, the work of the heart is greatly increased.

This can create symptoms such as:

• Rapid heart rate, even at rest and especially after exertion
• High blood pressure
• Heart palpitations
• Increased cardiac output (the amount of blood the heart pumps through the body)
• Increased pulmonary artery pressure (this vessel moves blood from the heart to the lungs)
• Chest pain

Once the hyperthyroidism is diagnosed, these people may find their symptoms have resolved with continuous treatment. However, an overactive thyroid raises the risk for other heart conditions.

These other disorders also can lead to palpitations and feelings akin to panic attacks. They are significant conditions that require treatment, including:

• 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 condition called toxic multinodular goiter, caused by nodules growing on the thyroid gland, also may cause episodes of overactive thyroid. These episodes can be a trigger for panic attacks or cause heart palpitations.

Hypothyroidism and Your Heart

The most common type of hypothyroidism in the United States is called Hashimoto’s disease. It can sometimes cause unpredictable releases of thyroid hormones, typically leading to hypothyroidism. Less often, it may lead to an overactive thyroid instead.

There are a number of other causes of hypothyroidism as well. They may include previous surgeries, the use of certain medications, an underlying genetic cause, or an autoimmune disease history.

When heart signs and symptoms do occur, they may include:

• Slower heart rate (bradycardia)
• Lower systolic blood pressure
• Higher diastolic blood pressure
• Lower cardiac output (the amount of blood the heart pumps through the body)
• Fewer heart contractions
• Shortness of breath after exertion
• Pericardial effusions (excess fluid around the heart)
• Edema (swelling) of the hands and feet

Another condition is very common in people with an underactive thyroid. It is called dyslipidemia and means that the lipids (fats) in your blood are abnormal. This condition raises your risk of heart disease, including the chance of a heart attack.

Additionally, heart disease itself may change levels of thyroid hormones in the body, such as causing low T3 syndrome, also known as nonthyroidal illness syndrome (NTIS).

This reciprocal relationship demonstrates the close link between thyroid function changes, and the influence of heart disorders as well as other critical illnesses. In fact, 70% of people admitted to intensive care units show signs of NTIS, which may suggest an increased risk of death.

Treatment

Usually, most people who have thyroid conditions find that once they're properly treated, the symptoms go away. These treatments may include medications, radioactive iodine, or surgery for people with overactive thyroids.

Hypothyroidism

Treatment may include hormone replacement therapy in people with hypothyroidism. Synthroid (levothyroxine) is the most common drug used for hypothyroidism. As a synthetic form of the T4 thyroid hormone, it can be used across a lifetime to maintain thyroid function.

Studies show that thyroid hormone treatment for people with an underactive thyroid helps to reduce heart-related risks. It remains less clear how such hormone therapy might benefit those who have a history of chronic heart failure or a heart attack.

Hyperthyroidism

Tapazole (methimazole) and Propylthiouracil (PTU) are drugs commonly used to limit the thyroid's access to iodine in the body.

Often, a blood pressure medication called a beta blocker is given too. These drugs include Inderal (propranolol) and Tenormin (atenolol). They don't treat the hyperthyroidism, but do ease panic-like heart symptoms such as a fast heart rate and palpitations.

You may need additional thyroid treatment measures if you have heart failure or other significant heart problems, or a severe hyperthyroidism diagnosis itself. For example, thyroid cancer may require surgery, radiation, chemotherapy, or a combination of treatments.

Other Potential Causes

If you've been treated for your thyroid and you're still having heart or panic attack-like symptoms, you'll need to see your healthcare provider. They will help you to sort out if thyroid disease is really what's causing these episodes or if something else is at work.

There are several other possibilities that may be involved, including the chance that you may not be taking your thyroid medicine as directed. You also may be more likely to have mitral valve prolapse (MVP) with a thyroid condition.

Mitral Valve Prolapse

Mitral valve prolapse (MVP) is a heart valve irregularity that disrupts how blood moves between two chambers of your heart. It is commonly seen in people with thyroid disorders.

People with MVP may see heart-related symptoms including:

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

This condition can be diagnosed by an echocardiogram, or medical imaging of the heart. There also are treatments, including the beta blocker drugs, that can alleviate your symptoms.

TSH Level

Your healthcare provider may need to check your level of thyroid-stimulating hormone (TSH). This TSH level may be high or low, though it's possible to have a normal reading with symptoms.

Low TSH levels are associated with hyperthyroidism, which may be due to a number of causes including an autoimmune disorder. High TSH levels are seen with low thyroid levels, and may be linked to your thyroid medication dosage or even foods that interfere with its absorption.

If your thyroid hormone replacement dosage is too high, and your TSH is at the lower end of the normal range, you may be borderline hyperthyroid. This is due to overmedication. In this case, it's worth discussing a therapy adjustment with your provider to see if it helps with your symptoms.

In the same way, if you're having periods of hyperthyroidism due to Hashimoto’s disease or toxic nodules, improved treatment may help resolve your panic and heart symptoms.

Mental Health Disorder or Heart Problem

If you and your healthcare provider cannot find a thyroid-related reason for your symptoms, you may, in fact, have a panic or anxiety disorder. You may also have some type of heart condition. In these cases, you should be further evaluated by a heart specialist and/or a mental health professional.

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

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

Summary

Symptoms that seem like they are caused by a panic attack or a heart condition may be just that. But in some cases, they may be due to an overactive or underactive thyroid.

When that's the case, many people find that their symptoms go away once their thyroid condition is treated. Talk to your healthcare provider about heart-related symptoms so that potential causes are evaluated and you can begin any related treatment.