Hypothyroidism And The Heart, by a Cardiologist

women with cardiac symptoms from hypothyroidism

I was searching for recently published studies on the connection between hypothyroidism and heart disease and there I found hundreds, yes hundreds, right before my eyes. Then one day a cardiologist from England contacted me with this guest post that everyone with hypothyroidism needs to read.

Written by Sanjay Gupta, MD

Deficiency of thyroid hormone can play havoc with your heart.

Cardiac symptoms of hypothyroidism

Cardiac symptoms that we see in patients with hypothyroidism include a slow heart rate. It usually manifests as a sinus bradycardia, meaning it is a normal rhythm just a little bit slower.

Secondly, sometimes we see exertional breathlessness, shortness of breath on exertion. They aren’t able to do as much without getting extremely tired.

The third thing that we see often in hypothyroidism is high blood pressure. In particular, we see both values, the top value (the systolic blood pressure) and the bottom value (the diastolic blood pressure), go up but the diastolic blood pressure goes up much more than the systolic blood pressure.

It is also worth noting that patients with hypothyroidism may develop swelling of their legs. What is typical about this swelling is that it tends to be non-pitting. When you press the swelling, the finger doesn’t leave a massive indentation behind.

Another thing we sometimes see in patients with hypothyroidism is the development of fluid around the heart. Up to 25 percent of hypothyroid patients may develop fluid which accumulates in the sac that the heart sits in, the pericardial sac. This accumulation of fluid around the heart is termed pericardial effusion. Pericardial effusions can grow quite big but usually they don’t have to be manually drained out because, as you treat the hypothyroidism, the fluid gets less.

Why people with hypothyroidism get heart symptoms?

The first thing to say is that the thyroid hormone thyroxine controls other enzymes which regulate, firstly, how fast our heart beats and, secondly, how strongly the heart contracts. Thirdly, thyroxine also controls how responsive our heart is to the hormone adrenaline. Another thing to know about thyroxine is that it relaxes all our blood vessels. It does this by its own effects but also by controlling the release of something called endothelial-derived relaxing factor (EDRF) which, again, opens up our blood vessels. And all of these processes can get affected if we are deficient in thyroid hormone.

The simplest way to think of this is that when we are deficient in thyroid hormone everything slows down and everything gets a bit stiffer. The contraction of the heart becomes less effective. Our heart rate slows down. The reason the blood pressure goes up is because of the stiffness of the blood vessels. The blood pressure goes up because the heart is having to pump against this stiffer system. Although less blood is going around because the heart is beating less strongly and more slowly and because of the stiffness, less blood is going around. This doesn’t really manifest as a major problem because the oxygen requirements become less because everything (the entire body) has slowed down in the hypothyroid person so all the tissues don’t need as much oxygen.

There was an interesting study where they took a bunch of people who had their thyroid removed as a result of thyroid cancer who were on thyroid hormone replacement. When you deprive them of thyroid hormone replacement, their diastolic blood pressure (the lower value) went up in about 20 to 40 percent of patients. The average rise in blood pressure is around 6 millimeters of mercury for the top value and about 9 millimeters of mercury for the bottom value.

As the heart slows down, patients with hypothyroidism may be more prone to developing ectopic heartbeats, extra beats. We see more ectopics in patients with hypothyroidism because the heart has slowed down.

It’s also worth noting another heart rhythm disturbance that can be seen in hypothyroidism is that, when the heart slows down, our QT interval will prolong. People who already have problems with their QT interval, who have long QT syndrome or people who are on lots of medications that prolong the QT or people who have underlying heart disease, are more prone to developing further prolongation of the QT. This can predispose them to a condition called Torsades de Pointes which is a risky and dangerous heart rhythm disturbance, but this is in a minority of cases.

Sometimes patients with heart rhythm disturbances are given a medication called Amiodarone. It contains iodine. One of the potential adverse effects is amiodarone-induced thyroid dysfunction (both hypothyroidism and hyperthyroidism).

For patients with heart failure and patients who already have pre-existing weak hearts, the development of hypothyroidism can make things worse. The heart is already not contracting as well and then hypothyroidism slows down the heart further and makes the contractions even less effective and it can exacerbate the symptoms of heart failure.

In patients who have angina, the presence of hypothyroidism actually helps. If you have angina, you have a supply and demand mismatch. When the heart needs more blood, it doesn’t get the blood it needs and the patient complains of chest pain. In hypothyroidism, angina tends to get better because the body’s requirements go down. The demand goes down and the demand and supply becomes more equal.

This is not to say that hypothyroidism is a safe condition because what we know is that the presence of hypothyroidism is quite inflammatory and it can accelerate heart artery narrowing if left untreated. 

In particular, hypothyroid patients also develop problems with their cholesterol metabolism and they get very high levels of LDL cholesterol, VLDL cholesterol, total cholesterol, and triglycerides. 

Patients with hypothyroidism also get blood pressure problems which again exacerbates the risk of developing stiffening of the blood vessels and the coronary arteries which leads to atheroma.

And we also find that, in patients with hypothyroidism, you can get elevated levels of homocysteine. Elevated homocysteine is a risk factor for heart disease.

Hypothyroid patients often get edema, swelling of their legs because of fluid in their legs, and the edema tends to be non-pitting. The way you can tell if the swelling is pitting or non-pitting is by pressing on the swelling. If your hand leaves an indentation that tells you that it is pitting. If it doesn’t leave an indentation then that is non-pitting. Typically, hypothyroid patients tend to get non-pitting edema. Patients with proper heart failure, which is another condition where you get a lot of edema, tend to get pitting edema. The reason hypothyroid patients get edema is largely because hypothyroidism increases the deposition of glycosaminoglycan which absorbs fluid which leads to accumulation of water in the legs and feet.

As you correct the hypothyroidism, most of the cardiovascular abnormalities you see tend to normalize. There are two important messages here. Firstly, it is important to be aware of hypothyroidism and to be aware that it can come on with non-specific symptoms including cardiac symptoms. If you notice you are getting a bit more tired, you are putting on weight, you are depressed, it is always a good idea to get screened for thyroid disease. Secondly, if you do develop these cardiac symptoms, know that as you treat the thyroid these symptoms will often improve in cases of hypothyroidism.

About Sanjay Gupta, MD

Dr. Sanjay Gupta is a cardiologist practicing in York, England. He believes in making high quality, jargon-free, holistic information about heart health freely available to everyone in the world. His research has been published in a number of publications including the Journal of CardiologyAnnals of Clinical BiochemistryCirculationEuropean Heart Journal, and Radiology. You can find Dr. Gupta on his website York Cardiology as well as his two YouTube channels More Than Just Medicine.

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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. John Hockett says

    What can a hypothyroid (a 7) left untreated for days, weeks, months do to person’s heart who has already had heart surgery (3 new arteries and 2 medal valves) both temporary and permanent affects?

  2. What info can you give on patiences who have lupus with low thyroid

  3. Louise Foreman says

    Hi I’d like to know if there is any difference and proof. Of this with taking different meds ie levothyroxine. Ndt /t3. My thyroid is now gone. I can only get levothyroxine on the nhs. And it made me so ill. So for the last eight years I’ve been self medicating on ndt. However getting much harder to get it. So trying to get ndt on nhs through my Dr. Was told ages ago needed t3 for a healthier heart.

  4. I have hypothyroidism and hand my thyroid removed. Triad is all since I wear 19 years old and I am now 48. 7 years ago I had open heart surgery due to a anurasim and also a bycuspid heart valve. I struggle daily with all the symptoms. I have always struggled with my weight. I need help. Please. Thank you

  5. Jane Ashley says

    A very good book to help with thyroid issues is Stop The Thyroid Madness. It can be found on Amazon and there is an edition with healthcare providers’ input. You will learn a huge amount from reading these books.
    NP Thyroid med was helping me so much until Acella Pharmaceutical changed the formulation. Now I’m on Armour which is ok, but I’m constantly fatigued and out of breath. So I’m not optimal yet.

  6. I had thyroid cancer 5 years ago my thyroid was removed my legs do swell and I have high blood pressure I have eye problems legs hurt stomach hurt that’s my problems they keep changing my medication every two months my levels has never been good for more than 3 months for the last five or six years

  7. Is it necessary/advisable to take medication to reduce your high blood pressure if it is caused by taking Levothyroxine ? [TSH .26 mcIU/dl. and Free T4 1.34ng/dL]. Endocrinologist stated finding the proper dosage should correct the problem. I have been on Levothyroxine since 1987

    • Bit tjeu aren’t going to figure out dosage by just testing tsh and ft4. You need the full thyroid panel and need optimal results, not just “in range”.

  8. Wanda Vail says

    I would like to recommend blogs written by Dr. Westin Childs, DO. Dr. Child’s switched from conventional medicine to Integrative/Functional medicine and never looked back. He closed his practice in 2017 to focus on educating physicians, formulating new supplements, providing blog posts and researching new topics. He has written 200+ articles on hormone balance, thyroid disorders and weight loss. I can honestly say that I know more about my hypothyroidism than the many PCPs and Endos I’ve been to over the years. Never once, in 42 years, did I have a doctor tell me that T4 is an inactive thyroid hormone and it needs T3 to activate it so it an get into your cells. I had a thyroidectomy due to cancer and went to many doctors over the years for help with my symptoms, but they didn’t know how or understand. After learning this from Dr. Childs, I mentioned this to my PCP and cautiously asked if I could try adding T3 (Cytomel or Liothyronine). Reluctantly, she started me on 5 mcg, then to 7mcg, now taking 10mcg. That doctor moved away. The third one I’ve been to since is “cautiously” letting me continue. My symptoms…no energy, weight loss resistance, brain fog, panic attacks, chronic constipation, sleep issues…have greatly improved. It was Dr. Childs that taught me this. He gives you suggestions for talking to your doctor and he provides case studies (I copied 15 pages) to back up his research. He recently posted a blog for people without a thyroid and recommended 9 supplements that we should be taking in addition to our thyroid meds. I will continue to “gently” be my own advocate since no one knows my body like I do.

    • Thank you for that excellent comment and recommendation. I am going to research more about that Dr as like many readers who have found themselves here, I am at a loss of where to go to get the help and advice I need to restore my well-being. (I have partial hypopituitarism and Hashimoto’s). I had hoped this article on the effects of the heart would be useful but I experience the opposite and have low blood pressure episodes which lead to fainting. It is such a convoluted journey seeking answers and so your type of comment here is much appreciated. I thought I’d just stop by and say thank you.

    • Hi im very interested in your post. Ive been taking oroxine for 16 yrs now. Diagnosed with graves disease. My weight has increased over the yrs and fatigue and mucsle stiffness just to name a few is getting worse. Im interested in what other medications that this dr suggested to you. Im a 42 yr old in Australia. My endocrinologist keeps increaseing my oroxine but nothing seems to help. Im an active person and a full time nurse and mum but nothing seems to shift my weight.

      • Amanda…
        Many of us hypothyroids do not convert T4 only meds to the useable T3 form in our bodies easily. This can be addressed by adding selenium and tyrosine to our list of supplements to help the thyroid convert. The T4 is getting converted to RT3 instead of T3. Getting your RT3 levels tested would be the first step. If it is elevated (see Janie Bowthorp’s website Stop The Thyroid Madness), then taking a T3 only med will help clear it. Then taking T4 and T3 will help keep you optimal. Janie has a link about what labs to request. Checking your adrenals with a 24hr saliva cortisol test would be a good idea as well as checking your ferritin and magnesium levels. Endocrinologists are really clueless about the thyroid and think throwing synthroid at it will cure us. It rarely does.

  9. Nicholette Deacon says

    I have had Thyroid problems for the past40 years i am now 81 my problem now is i have thyroid eye diseise very bad double vision. had 2 oporations on both eyes and has not corrected the problem its very frustrating as i am unable to go out unles with company because i have problems with curbs, stairs, and treffic, I do have some of the other symptoms but i cope with them but the double vision i find really difficult

  10. Patience Mambo says

    I have found this information to be so insightful and relevant. Thanks

  11. I’m hypothyroid- Hashimoto and ive had 3 ephysiology studies with ablation bc many years I was supraventricular tachycardia , at the time with an undiagnosed thyroid. All clinical symptoms pointed to hyperthyroid but the lab came back hypothyroid. I’m 5’7 and my body weight went to 104. I’m back to 125 but still not ideal weight. Thyroid disease has a long way to go with research.

  12. I was diagnosed 2 years ago. I’ve been having symptoms for over 20 years. Every doctor so far has sent me to another Dr. No one can figure out what’s going on. Had a heart attack last year Endo said thyroid does not cause heart attacks. Heart Dr said thyroid caused the heart attack. I’m tired of fighting the Dr . The last one told me to seek therapy all in my head.

  13. This is valuable information. I experience some of the issues mentioned. I haven’t been on thyroid meds for years they did not do anything for me. Dr get offended when you ask them to do specific tests. With this addition information I keep on searching for a supportive Dr. I will share this with some friends. Thanks for sharing this information.

  14. It amazes me how little dr know and understand about Thyroid issues. I had total hysterectomy couple years ago and my world fell apart! It was all due to hormones and thyroid. Took almost 2 years to figure out what was causing all my different issues. I was the one that figured it out, not my Dr. He finally asked me one day if I was over thinking things/my issues. (Yes, I was severely pissed at him and his remarks). It all started about 6 months after hysterectomy, with quickly changing vision, then shortness of breath and heart palpitations. I was also having a lot of upset stomach w/ nausea. Then my blood pressure was fluctuating and it’s always been low. I had all sorts tests and no answers. Finally saw someone post on a friend’s Facebook about a functional medicine Dr and her hormone therapy. Major game changer. My primary care dr said my thyroid was fine. The functional med Dr disagreed and started me on NP Thyroid.

    • Can Jennifer tell me more about her Functional doctor’s approach? I’m 61 and just this morning was diagnosed with Hasimoto’s Disease (HD). My BP and heart rate have been low for a while. Reading the article above possibly links this to HD. Scheduled for a biopsy early March (two enlarged nodules). I am researching naturopaths and/or Functional Medicine. I’d appreciate feedback from anyone who has experience treating hypothyroidism this way. Thank you, Jami

      • I read a book on Hashimoto protocol. Some library’s have it and it helped me to understand Thyroid issues. Also Dr Hyman on Instagram has been doing research for many years he was the first Dr I learned about hypothyroidism.

      • Christina Gold says

        Apart from Hashimoto’ s disease which is an auto-immune inflammation of the thyroid,
        given the result of your pending thyroid nodule biopsy you my have an under-functioning thyroid due to an adenoma (benign) of the thyroid.

        Mine was removed with and I have been on thyroid medication ever since. Just like you I was diagnosed with Hashimoto’s at age 69. My thyroid levels always tested normal. Until then I never had my thyroid antibodies tested, the results came back very high.
        Basically I was told that there was little I could do about it.

        Not wanting to accept that opinion I started to search for information on the computer and found three books written by Izabella Wentz, a pharmacist. All three books are available on Amazon. Ms. Wentz had Hashimoto’s and has done intensive research into the subject, all gathered in the books.
        The most important take away for me was the link to gluten intolerance with 75% of people she monitored. I have always wondered why I could not lose that extra 15 pound of weight with regular exercise and a decent diet.
        That was answered for me through DNA testing by 23 and Me which I did 7 years ago, sending me even now genetic information. A year ago they told me that I was gluten intolerant and that I have one gene for celiac disease.
        Diet is a big factor in Hashimoto’s and certain substances are beneficial, like Selenium a mineral which aids to protect cells. Ashawagandha, a adaptogene can help with auto -immune conditions.
        Hoping that my limited information helps you to learn more about your condition.
        Reading the above article, having the described BP problems occasionally which worried me, gave me the insight that many cardiologists will be better in connecting the link between certain conditions. More and more of us can control our healthcare information on the computer. In the past medical doctors had to sort through badly hand written stacks of medical records. If your health care provider offers this system, you will love it. All the information about your health history is easy to read and concise because you have access to it and can correct mistakes and helps physicians to access information faster.

        Kind regards,

        Christina Gold

        • Vickie Karnes says

          I need help my family thinks I’m crazy and my Heath issues I make up. I need new drs to hep me and the cold weather is horrible for me. I eat all the time yet weight less every day. My right foot swells all the time and I’ve been not feeling my best at all 2021. I live near Charlotte NC just got medical equipment last week. Im 63 and depression will soon kick my butt. How can I get my family to understand how serious my health is. They are clueless. 🛌❤️💗💟

          • I’m sorry to hear you are struggling Vickie. It is hard for people that do not have thyroid disease to understand what it can do to a person. I brought together great thyroid doctors for the Hypothyroid Mom Centers to help people struggling to find help. While the locations may not be near you, there is the option to join as an Exception that’s fully virtual that is all done virtually from your home. Here is the webpage with the description of services: https://bit.ly/HMCenters

            There is hope to be well with hypothyroidism.
            All the best,
            Dana Trentini (Hypothyroid Mom)

  15. Everyones Thyroid is out and should have a FULL Thyroid panel test. could save alot of lives. Be your own health advocate. tell your Dr. has to be a Full panel tho

  16. I found this very informative. Especially since over the past year or so my blood pressure numbers have been whacky. It seems most doctors aren’t aware of all the issues that come with hypothyroidism.
    I’m currently on naturethroid. Although my numbers appear good my blood pressure and swelling isn’t. I need recommendations. Thank you

    • Sandy P in NC says

      I haven’t actually started taking it yet, but I did research thyroid drugs with no fillers and came across Tirosint. My insurance does not like it, so I am on my own. I am in the throws of getting a written prescription to a specialty pharmacy out of state. There is a program called Tirosint Direct, where I can get 30 pills for $50 and 90 for $120. Better than AARP Medicare Drug Plan of $132 for 30 pills. Anyway, it’s my last hope. I have been through the wringer with shortness of breath, diarrhea, palpitations. I went to the endo within six weeks of beginning the Levothyroxine. Both the Duke Endo and her NP told me it was not the Levothyroxine and sent me to my primary doctor. I have been sent for a myriad of tests, both cardiac and pulmonary. I underwent a sleep study. Found to have Obstructive Sleep Apnea. When using the CPAP I developed Central events. Now I am awaiting the Corona Virus to abate somewhat so I can have the Inspire implant procedure for that. Meanwhile I still suffer from breathlessness for over nine months now. Only the cardiologist listens. My PA just recently said she would try a new medication. I think I am annoying every medical person I see, but it IS my life we’re talking about here.

      • A. Dillard says

        Another thyroid replacement you might want to look into is Armour Thyroid. It is made from the natural pig hormone and has both T3 and T4. Additionally, using Synthroid instead of Levothyroxine may help. I crashed when taking the Levothyroxine, which is generic Synthroid, but am fine on Synthroid.

        Best wishes.

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