Is Your Thyroid KILLING You? Heart Disease

Thyroid & 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.”

Cardiologist Dr. William 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.

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 and natural desiccated thyroid turned out to be my body’s magic formula.)

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 World Health Organization estimates that thyroid dysfunction affects 750 million people worldwide and the American Thyroid Association warns that up to 60 percent of those with thyroid disease 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. NewsWise. American Thyroid Association Announces 7th Annual World Thyroid Day May 25, 2014. Retrieved from:

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I appreciate every share! Thank you.

About Dana Trentini

Dana Trentini founded Hypothyroid Mom October 2012 in memory of the unborn baby she lost to hypothyroidism. This is for informational purposes only and should not be considered a substitute for consulting your physician regarding medical advice pertaining to your health. Hypothyroid Mom includes affiliate links including the Amazon Services LLC Associates Program.


  1. Glen charles says

    my symptom was not being able to breathe when lying down basically . I’ve kind of resigned to the fact that this is how life will be for me back until I found herbs that stop this CHF easily and relief all the airways. My wife and her caregiver assume I can’t be as active, and thus I was excused from normal life responsibilities but natural herbs from www. totalcureherbsfoundation. com really helped a but sometimes I think is God prodigy that I was able to treat my congestive heart failure but total cure herbs foundation herbal formula has a big impact on my recovery because my heart condition has been fully eliminate, during your order you have choose the AATD herbal remedy on their website order list to get the right treatment for Congestive heart failure . They do things for me, and was too happy to comply with their service. This is a equitable of a way to get of your heart failure.

  2. Glen charles says

    I am 58 years old, and was diagnosed with heart failure over a year ago. My main symptoms was fatigue, shortness of breath, and a general sense that these symptoms will keep me out of normal life activities, my symptom was not being able to breathe when lying down basically . I’ve kind of resigned to the fact that this is how life will be for me back until I found herbs that stop this CHF easily and relief all the airways. My wife and her caregiver assume I can’t be as active, and thus I was excused from normal life responsibilities but natural herbs from totalcureherbsfoundation. com really helped a but sometimes I think is God prodigy that I was able to treat my congestive heart failure but total cure herbs foundation herbal formula has a big impact on my recovery because my heart condition has been fully eliminate. They do things for me, and was too happy to comply with their service. This is a equitable of a way to get of your heart failure.

  3. Gillyanne Fisher says

    I have been subclinical hypothyroidic for several years. Also borderline. Recently developed AFib but all medics have told me is that hypOthyroidism is not a factor, Only hyper. Please point me towards relevant articles. Cheers from the UK

  4. Stephanie says

    I have been on Synthroid for 19 years. I was diagnosed with idiopathic cardiomyopathy 10 years ago and recently had an AICD placed. My doctors refuse to acknowledge that the Synthroid is the cause of my heart problems but cannot tell me what else is causing it. I am so frustrated and feel like there’s no hope. Can someone recommend a good Endocrinologist in the CT or NY area?

  5. Over the last year my thyroid numbers and symptoms have been all over the place. About 16 months ago a naturopath added Armour (5) to my levo (125) and in ~some~ ways I felt better. I moved and it took a bit to get into a new ND. After labs she kept me on both Armour and levo and ran labs including food allergy tests. After eliminating those foods I felt pretty good and then I think maybe my thyroid started working a bit better. I began having some hypErthyroid symptoms (poor sleep, unneeded weight loss, racing heart). I went to an MD (left the ND for other reasons) who seems open-minded about thyroid who checked my T3, T4 ,and TSH. T3 was in the lower quarter of standard range, T4 hugging the top, and TSH quite suppressed. I went off Armour and the racing heart was much better. Poor sleep and weight loss continued. New labs still showed suppressed TSH so we went to levo 112mcg. Sleep better but still not great. Weight loss stabilized. New labs still showed suppressed TSH but 10 days in I am having horrible fatigue. My heart feels like it doesn’t have the energy to beat! I have a call in to the doctor to see if she will raise the levo back up to 112mcg. I didn’t feel great on 112 but it wasn’t scary like this.

    One question I have is does anyone know if it’s T4 or T3 that suppresses TSH? Just wondering if maybe just T4 suppresses it. Wouldn’t that be interesting if T4 is what suppressed TSH even if T3 is low. Maybe I just have a T4 to T3 conversion problem. The doctor did suggest I may be iodine deficient. This is possible because when I do use salt it’s typically Himalayan pink salt or Real Salt which are not fortified. My diet is clean, although I have recently been diagnosed with SIBO and taking steps to deal with that.

    The current medical establishment just doesn’t seem to understand how the body works, and doctors are not interested in really listening. They are so focused on rote memorization of symptoms and the medications they were taught in school they are doing more harm than good. The pharmaceutical companies (and now the insurance companies) have a death grip on all of us. Maddening.

  6. Brenda Gardener says

    Research and determination is required. A willingness to fight for your health and clean up your diet. I had an officious endo who blamed me for 3 years for the erratic readings. Fed up I requested a referral to a more modern doctor. I paid for RT3 tests and full blood work. A stint on T3 and now I have stabilised on a natural porcine thyroid extract. $$ expensive but my health is worth it. Gave up gluten and added zinc and Selenium drops plus extra D3 at my new endocrinologist suggestion. Find a medical practitioner who will partner with you for good health.

  7. Good grief. People looking for answers to their thyroid problems don’t need to read a headline that my thyroid may be “KILLING” me.

    • western influences.. are killing you.via cross contamination.. and exposure to round -up.low t3 is never correct.for those with celiacs or IBS. whilst American Medical profesionals.. will watch your immunity health and humanity crumble. 70 percent of celiacs suffer from hypothyroidism. If we were allergic at birth, we would all be on TLC with the wee people. genetics loads the round.environment pulls the trigger

  8. Carissa Bruce says

    I’m hypothyroid but as soon as I start any thyroid medication I get chest pains and shortness of breath. I’ve tried Synthroid and Cytomel combo and Armour. I just recently went to the doctor and I have a irregular heartbeat now as well. I’m in good shape and 36 years old. Please help! I need to take the meds but I feel like my heart can’t tolerate it. When I go off meds heart issues go away but I gain weight rapidly.

    • I am 35 years old with type 1 diabetes . About a year and a half ago ,I was diagnosed with hypo ,and for about a year ,Everything went well.
      Fast forward to now , I gained a ton of weight ,hair has fallen out ,heart palpitations are horrible ,and ….. I was over treated for many months. Before my diagnosis,I was 128 lbs at 5’5 ,and now , I’m right at 150 within 6 weeks. .
      I never feel good ,always exhausted,can’t get pregnant,and I am getting depressed.
      Living a healthy lifestyle has always been a thing for me ,and now , No matter what I do ,nothing works. My endocrinologist actually told me my thyroid wasn’t my issue and that this was all in my head. Mind you ,20 lbs in 6 weeks ,heart problems, high t3, great tsh. What should I do ?? I feel like my life has been torn away from me. .

    • Lower you dose.

    • This is exactly my situation! I have tried Naturethroid 65mcg and I started to feel better but my TSH was still a 42 after 2 weeks. My T3 was normal at that point. When my doc wanted to increase the naturethroid to help the TSH, I started getting chest pains and shortness of breath and anxiety problems. I think it’s from too much T3. I’m currently reading Dr. Arem’s book on thyroid. He’s a prominent doctor that my mom went to in 2000 to treat her hashimoto’s. There’s info in the book about how to start dosing and how to combo the meds. He says you should only increase by 25mcg a week so that you don’t get those heart/anxiety symptoms. I’m still in the learning phase though and I’m not sure if my doctor has a good plan of action…

    • Some people don’t respond well to T4. I am one of them, I cannot take more than 50mcg Levoxyl daily without experiencing high anxiety. So I take 25mcg T3, along with 50mcg T4, which works well. Some patients cannot tolerate ANY T4. I used to be in that boat, and while I was, I used T3-only. Almost all thyroid patients treated with T3-only, who keep their FT3 in middle of the range, will feel well.

  9. Cindy Baciak says

    I feel that my thyroid is not working right either….so fatigued and weak….but we have high toxic chemicals aerated in in rural WIS. including chlorine…. and that screws up the iodine your thyroid needs….and you need to detox your thyroid, chlorine can stay in that gland for months…. and BP meds won’t detox your gland, and neither will thyroid meds…in my opinion….that is just one of the things that could be affecting people, also drinking chlorinated water, or swimming in chlorinated pools….

  10. I was recently diagnosed with Hypothyroidism when I started having heart palpitations for the first time in my life. First I was having pain in my neck that shoots up to ear and literally within hours the palpitations started. My blood pressure is not stable at all. It goes from low to high. When the palpitations and the neck pain start the lightheadedness sets in and the exhaustion. I mean like exhaustion like I have never experienced in my 45 years and I am a Mother of 5 children.

    I went to my first visit with the Endocrinologist and he started me on low dose levothyroxin 50mcg and I have been on it for 13 days. The palpitations are so concerning and I keep getting told that it is a sign of an overactive Thyroid but my labs show that my Thyroid is underactive.

    This is all so confusing and I am trying to educate myself on what my options are for treatment. Any advice would be much appreciated!

    Thanks so much!

    • Journey S Dell says

      Hi, sorry to hear you are so stressed. I’ve had thyroid issues since I was a child, but only now at 72 am I spending the time to really educate myself and read a good deal about the thyroid, thyroid meds and herbs that are available. I’d suggest you take the time, right now, to educate yourself. I wish I had educated myself years ago instead of just trusting my Dr.s and maybe the autoimmune disorders, that they’ve kept me homebound for many years, would not have become so predominant. My GP MD, at my request, switched me from Synthroid to NP thyroid a few weeks ago. I’m now in my 2nd week of a low dosage of NP thyroid and I’m going to start taking the herb Ashwagandha next week. Also I see my endo for the 1st time in 2 weeks.I know all this info, meds and diet are confusing, but keep at it and have faith that it will get easier to understand what you need to do to help yourself and I’d suggest…never stop learning about what could be helpful. I’m glad I finally realized that myself.

    • I found a functional medicine site that puts it all together and gives nutritional guidance: Everything finally made sense. It’s sensible information that has greatly helped me and put me on the road to recovery….naturally. I was suffering from panic attacks, insomnia, chest pain, low temperature and pulse, and debilitating fatigue before changing my diet and using natural supplements.

    • Amnah Rawlings says

      Hi mish me to have been diagnosed with under active thyroid I’ve been so ill the last year thinking it was menopause or just getting old am only 50 but felt like I was ready for the knackers yard . The palpitations pains in my arm the not. Ring able to swollow properly as well as the walking which am out of breath with plus palpitations not being able to walk straight was another . Well finally got an answer 3 weeks ago now started on the 50 but honestly can’t say they have helped now after going to accident and emergency thinking I was having a heart stack everything pin pointed to it nothing showed only now I had a large heart which I’ve never known high blood pressure which I never had and now I get told because I’ve suffered with this underactive thyroid secretly for over a year now have heart muscle causing the pain so now have to go for a heart scan to see what damage had been caused I’ve also got white patches all over my skin were urs destroyed my pigmentation it’s been a nightmare the last few weeks adjusting and coming to terms how this one thing can change everything about me .

  11. Heart disease is not from high cholesterol, it is from inflammation. Your brain and every organ need cholesterol to work correctly.

    • I need someone to convince my Doctor of that. High Blood Pressure is another thing.

    • keith loreth says

      Heart disease is connected to low Vitamin C and the amino acid lysine.

    • Cholesterol (the good one – HDL) is very necessary. Your brain even needs it. In this low fat, low carb obsessed world we have forgotten (or maybe been unaware) of how much fat (healthy fats – avocado, nuts and seeds, olive oil, coconut oil and others) plays a key role in brain function. The brain is made ip of nearly 60% fat. It’s essential to consume healthy fats on a daily basis. Statin medications are used to lower cholesterol FAST, but are not meant to be used as a lifelong therapy. The risks far outweigh the benefits. Hypothyroidism is associated with elevated cholesterol levels, blood pressure, hair growth, muscles pain, joint pain (arthritis), vision problems, rashes, cold intolerance, fatigue, brain fog, swollen legs and ankles, puffiness, hoarse voice, depression, difficulty focusing, insomnia, weight gain, and over 100 more issues. I was prescribed Prozac when I was first diagnosed because of my depression (luckily temporary). Little did I know then that depression is one symptom that is not usually associated with hypothyroidism. I urge everybody to educate themselves as much as possible. Read up on the latest therapies, medications, protocols, and talk with your foctor about your findings. If your doctor is not receptive and is not willing to at least try new protocols, then it’s time to move on to someone who cares more. Functional medicine physicians treat the body as a whole. Not just one broken system vs another. We are one machine with interconnected components. Medicines help if they are managed right. But you have to treat the body right with healthy eating and healthy living. You are, after all, the one who cares about yourself the most. I hope I have been of some help.

  12. Something strange has happened to my TSH levels and they have gone down to .01 way below the standard, while my FT4 is at .70 nd .80 and my FT3 is at the bottom at 2.22 when taking a drug that increases FT3 it is at 2.50. My normal FT3 in the past was 3.5. When my FT3 is 2.22 to 2.50 my blood pressure goes up and my cholesterol sky rockets. This went on for two years. I think I was on the way for heart attack when my doctor finial relented and increased my Natur-throid by .o5. After the second day my blood pressure has come down from 160/78 to 121/68. I frankly am scared because of my TSH.

  13. JoCarole Carpenter says

    I never had any heart problems until after I was dx’d with Hashimotos. Now I have a heart murmur.

  14. nature thyroid?

    • Perhaps Katy meant NatureThroid, a brand name for natural dessicated porcine thyroid, similar to Amour Thyroid. Not sure, just a guess.

  15. My heart palps stopped when I raised my nature thyroid

  16. Hello,
    All this talk about heart disease is new to me. I just got my thyroid removed and it was cancerous. I have been having irregular heart beat 180 bpm twice now and I am just now reading the importance of T3. What do I do? Ask my doctor to test for T3. I have never heard her talk about T3 on T4.

  17. I had hypothyroid past 17 years . Now I take thyronorm 75mg. Now my problem is pulse rate is raising and bloodpressure is up and down. Please give me some advices my health.

    • I had hypothyroid for 10 yrs but only diagnosed 4 yrs..armour thyroid was tried for 1 years but blood pressure was high all the time..I was switched to levothyroxin, took it for a year, npr still high..I read that combining t3 & t4 works for some..I tried taking my left over med armour thyroid in am & levothyroxin at evening..I keep it 12 hours blood pressure went down immediately after the first day…I started it New Year..Am still doing it. Am so relieve that my blood pressure is now normal..o haven’t told my doctor what I did. She always objects trying new approach to treat me..Am looking for a different m.d.who is more open minded rather than sticking to the old conventional approach.

      • Dr. Irwig in Washington, DC is a fantastic and sympathetic endocrinologist who compassionately/kindly helped me get thyroid problems under control. I am grateful everyday for having crossed paths with this wonderful doctor 👨‍⚕️

      • Can you share your diet? I have “normal” blood test results, but I have constant weight battles on a keto diet, and zero periods for 4 years. I am 25.

      • I was diagnosed with Hypothyroidism 20 yrs ago and have been on long journey trying to manage this condition. I have to ask my doctor to perform blood test for T3 and T4. If don’t ask she won’t do it. I have yet been able to get a response when inquiring about the right number for me….we have heavy discussions about a range. She can’t tell me! My sister has Hyperthyroidism and the radiation treatment. Just recently discovered heat was functioning les than it should be. After several visits and stays in the hospital, she is now equipped with a pacemaker and defibrillator and was told her thyroid problem is the cause. I’m afraid this will happen to me if I don’t get the proper dosage. Thank you for your article and list of doctors. I will be looking for a new one. Also. If you could share your diet, that would be great.

      • How will you greet refills if they don’t know what you’re doing?

      • Please if you could help me anyway that would be great I feel like I’m at the end of my rope and I don’t know how much longer I can continue to do this on the daily

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