The Thyroid/Heart Connection

By Dr Ernst
August 12, 2021

The thyroid is a butterfly-shaped gland located in the center of the neck just below your Adams apple. It is known as the “Master Gland” due to its ability to regulate a complex system of other hormones and organs in your body – specifically your heart.

All it takes is a look at the symptoms of irregular thyroid function and you can quickly see how the hearts and thyroid are closely connected:

High blood pressure, Low blood pressure, Slow/weak pulse (under 60 bpm), Fast pulse (over 90 bpm at rest), Arrhythmia (irregular heartbeat), Skipped beats, Heart palpitations, Chest pain, High cholesterol, High triglycerides, High LDL (“bad”) cholesterol, Mitral valve prolapse, Atherosclerosis, Coronary artery disease, High C-Reactive Protein ,Fibrillation, Plaque buildup, Fluid retention, Poor circulation, Enlarged heart, Congestive Heart Failure, Stroke and even Heart attack

The connection becomes even more real when you look at what the scientific literature has been publishing on this matter since the mid 2000s.

Circulation is a scientific journal published for the American Heart Association that publishes articles related to cardiovascular diseases. In 2007 an article appeared entitled Cardiovascular Involvement in General Medical Conditions: Thyroid Disease and the Heart:

The cardiovascular signs and symptoms of thyroid disease are some of the most profound and clinically relevant findings that accompany both hyperthyroidism and hypothyroidism. On the basis of the understanding of the cellular mechanisms of thyroid hormone action on the heart and cardiovascular system, it is possible to explain the changes in cardiac output, cardiac contractility, blood pressure, vascular resistance, and rhythm disturbances that result from thyroid dysfunction. The importance of the recognition of the effects of thyroid disease on the heart also derives from the observation that restoration of normal thyroid function most often reverses the abnormal cardiovascular hemodynamics.

According to the Thyroid Federation International:

The heart is a major target of thyroid hormones. Any change in thyroid hormone levels will be responded to by the heart.

Too little thyroid hormone as a consequence of an under-active thyroid (hypothyroidism):

  • causes your heart to beat too slowly or irregularly, to flutter with missing or additional beats. As a consequence bradycardia may develop; this form of arrhythmia leaves your organs and tissues without enough oxygen and nutrients. Severe bradycardia can result in cardiac arrest.
  • causes your blood pressure to change. Over time, high blood pressure will develop with the consequence of developing atherosclerosis, a risk for heart attack and stroke.
  • causes your cholesterol in the blood to rise and calcification, so called plaque, to develop in your arteries and makes them stiff. All these effects increase the risk for heart attack, heart failure and atherosclerosis

Thyroid Hormone And Your Heart

In the pharmaceutical world, Levothyroxine is the most commonly prescribed thyroid hormone replacement drug, with brand names including Synthroid, Levoxyl, Oroxine and Eltroxin. Levothyroxine drugs contain the synthetic form of only ONE thyroid hormone, T4. T4 is only one portion of the thyroid hormone complex. Yes the majority of thyroid hormones produced by the human thyroid gland are T4, however T3 is the most active useable form of thyroid hormone that can be used in the cells of the body. The conversion of T4 to T3 is a critical element in this puzzle. By doctors strictly relying on T4-only medications, they are under the assumption that our bodies are properly converting the T4 to active T3. For many hypothyroid sufferers like me, our bodies don’t convert T4 to T3 properly.

TSH (thyroid stimulating hormone) is the “gold” standard for thyroid diagnosis and treatment in mainstream medicine. Traditional doctors will test TSH and sometimes T4 levels when they suspect thyroid dysfunction, however many do NOT test Free T3 levels or Reverse T3. Many traditional doctors will NOT treat patients with natural or synthetic T3 drugs even if their patients are not doing well on their T4-only drugs. This focus on TSH and T4 in mainstream medicine is particularly disturbing to me considering the studies published linking low Free T3 levels to heart disease.

In one study, a total of 573 consecutive cardiac patients underwent thyroid function profile evaluation. Based on the results of the 1-year follow-up:

“Low T3 syndrome is a strong predictor of death in cardiac patients.”

In another article published in 2010, researchers wrote:

“several clinical observational studies showing the important role of a low-T3 state in the prognostic stratification of patients with Heart Failure. Independently of the parameter used, all of these studies showed that impaired T4-to-T3 conversion is associated with a high incidence of fatal events consisting of cardiac or cumulative death or of heart transplantation.”

Dr. William Davis is a renowned cardiologist and author of the #1 New York Times Bestseller Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back to Health. Dr. Davis wrote an article in 2007 for Health Central,T3: The forgotten thyroid hormone. He wrote:

What does this have to do with your heart? There’s no question that low thyroid hormone levels act as a potent risk factor for coronary heart disease. While we’ve known for years that people with congestive heart failure or are seriously ill have abnormally low T3 hormone levels, two studies have recently found that people with coronary heart disease also have low T3 levels. These two studies now raise the question of whether low T3 by itself could be associated with increased risk for heart disease.

Could there be people on statin drugs and blood pressure medication right now who are actually undiagnosed hypothyroidism sufferers? Or could they be hypothyroid patients insufficiently treated for their condition?

All the heart disease patients lined up to visit cardiologists, could some of them actually be undiagnosed or insufficiently treated hypothyroid sufferers?

All the heart surgery patients, were they tested for thyroid dysfunction before the medications were prescribed and surgery performed?

All our loved ones who have died of heart attacks, strokes or other heart disease complications, did they ever have their Free T3 levels tested?

According to the World Heart Federation, heart disease is the number one killer of women around the world. The Thyroid Federation International estimates there are up to 300 million people worldwide, majority women, with thyroid dysfunction, yet over half are unaware of their condition.

It is critical to think about these questions while considering treatment options, and luckily there are plenty of ways to treat and heal the thyroid naturally.

To learn more about the Thyroid & Heart connection and to discover your options for proper testing and therapy, request a free 15 minute consultation with Dr. Aaron Ernst, D.C. today.

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