Is Your Thyroid KILLING You? Heart Disease


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
Coronary artery disease
High C-Reactive Protein
Plaque buildup
Fluid retention
Poor circulation
Enlarged heart

Need I say more?

“Dana, your cholesterol is very high.”

“Dana, your blood pressure is extremely low.”

“Dana, your heart rate is too low.”

“Dana, your Cardio CRP (c-reactive protein) is far above the normal range.”

Thyroid Disease & The Heart

Within the very first hour that I spent researching the link between heart disease and hypothyroidism, I found hundreds of published scientific studies. Goose bumps rose on my arms as I stopped and stared in shock at what I had discovered.

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:[1]

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:[2]

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 underactive 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

T3 Thyroid Hormone & The Heart

In mainstream medicine, 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. Please read my post Top 5 Reasons Doctors Fail To Diagnose Hypothyroidism.

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. Many traditional doctors will NOT treat patients with natural desiccated thyroid 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:[3]

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

In another article published in 2010, researchers wrote:[4]

“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 hormoneHe 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.

If your doctor refuses to test Free T3 you can order your own lab testing. Yes you can!

Dana, Your cholesterol, heart rate, blood pressure, and Cardio CRP have all improved.

My primary care physician shakes his head in amazement. (I had searched for a great thyroid doctor who explored the thyroid treatment options to find what was right for me. A combination of  natural desiccated thyroid and time release compounded T3 changed my life.)

That’s amazing.

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? Hmmm….

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

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

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?  Hmmmm…..

According to the World Heart Federation, heart disease is the number one killer of women around the world.[5] 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.[6] Hmmm…


1. Klein, I., Danzi, S. Cardiovascular Involvement in General Medical Conditions: Thyroid Disease and the Heart. Circulation 2007; 116: 1725-1735.

2. Thyroid Federation International. Thyroid and heart. Retrieved from:

3. Iervasi, G MD, et al. Low-T3 Syndrome: A Strong Prognostic Predictor of Death in Patients with Heart Disease. Circulation 2003;107:708-713.

4. Gerdes, A.M., Iervasi, G MD. Contemporary Reviews in Cardiovascular Medicine: Thyroid Replacement Therapy and Heart Failure. Circulation 2010;122:385-393.

5. World Heart Federation. Women and cardiovascular disease. Retrieved from:

6. Thyroid Federation International. Be Thyroid Aware. Retrieved from:


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