Thyroid Not Happy? How Thyroid Affects the Heart

By Angela Hartley on 16 April 2021

Did you know that thyroid affects the heart?

Perhaps you’ve been told you have a thyroid problem but have been taking the same medications for it for years and don’t really feel any better? Or you’re unsure how thyroid affects the heart? 

Here’s what you need to know about the thyroid and how thyroid affects the heart. In this article, I will teach you how to keep your thyroid healthy.

What is the thyroid?

In order to understand how thyroid affects the heart, it is vital to know where it is located.


The thyroid is a butterfly-shaped gland in your neck, just behind the ‘V’ where your collarbones meet. It produces hormones – thyroxine (T4) and triiodothyronine (T3). Thesee hormones tell your cells if they need to speed up or slow down. These hormones handle energy production, heart rate, hair growth, and heat production.

Does the thyroid affect the heart?

Thyroid hormone is a very important hormone for normal heart function, but if the thyroid gland is overactive or underactive, the result is a number of consequences. Sometimes, it even involves the heart.

Certainly, the connection to the heart is well established, but thyroid problems are often overlooked as the cause of heart problems. Your doctor should check if you have the following:

  • Arrhythmia (fast, slow or irregular heart rhythm)
  • High blood pressure
  • Heart failure
  • Heart disease or hardening of the arteries

In addition, thyroid disease affects the heart when it produces too little thyroid hormone (called hypothyroidism) or too much thyroid hormone (hyperthyroidism). Both types of thyroid disorders are common and can affect the heart.


Hypothyroidism affects approximately 80% of people who have a thyroid disorder. Hypothyroidism indicates that the thyroid is not producing enough thyroid hormone or the body is attacking the thyroid gland and thus the gland becomes spongy and ineffective. 

For example, Hashimoto’s thyroiditis is the most common cause of hypothyroidism, which is an auto-immune condition in which the body’s immune system gradually destroys the thyroid gland. As a result, the amount of circulating thyroid hormone in your body is too low.

Symptoms of Hypothyroidism

  • Fatigue
  • Feeling tired in the morning, even after sleeping well
  • Feeling cold a lot of the time
  • Weight gain and difficulty losing it
  • Hair loss
  • Dry skin
  • Muscle loss
  • Poor digestion
  • Low libido
  • Depression or low mood

Effects of hypothyroidism

In terms of the heart, you may not be able to SEE what is happening, but hypothyroidism can lead to:

  • Hypertension (high blood pressure)
  • Diastolic dysfunction, where the ventricles or ‘pump’ of the heart do not pump as strongly, which can lead to heart failure
  • Bradycardia (slow heart rate)
  • Heart palpitations and atrial fibrillation

One of the most important reasons to find out what is going on with your thyroid is because without treatment you will continue to have symptoms and a heart condition can result from being untreated. 

In a person who has almost any type of heart disease, disorders of the thyroid gland can worsen cardiac symptoms or cause new ones and can accelerate the underlying cardiac problem. Thyroid disease can also cause new heart problems in people with otherwise healthy hearts.


An overactive thyroid, also known as hyperthyroidism, is where the thyroid gland produces too much of the thyroid hormones and thus the hormone levels rise.

The thyroid can become overactive due to a number of factors, including:

  • Graves’ disease – where the body’s immune system mistakenly attacks and damages the thyroid
  • Lumps (nodules) on the thyroid – this results in extra thyroid tissue, which can mean extra thyroid hormones are produced
  • Certain medications – such as Amiodarone, a medication for atrial fibrillation

Symptoms are quite different from low thyroid hormones and can include:

  • Nervousness, anxiety and irritability
  • Mood swings
  • Difficulty sleeping
  • Persistent tiredness and weakness
  • Sensitivity to heat
  • Swelling in your neck from an enlarged thyroid (often called a goitre) 
  • Palpitations or atrial fibrillation
  • Twitching
  • Weight loss

Checking your thyroid

Talk to your doctor about your symptoms and ask if it could be your thyroid. If you haven’t had one recently, they should take blood to check on your thyroid function.

Have your doctor examine your neck to see if your thyroid gland is enlarged.

Here are the results to look for when looking at your blood tests and what they may mean.

If all levels are normal but you have Thyroid Antibodies in your blood, this could be Hashimoto’s Hypothyroidism.

Talk to your doctor and make sure that they are giving you the correct treatment and monitoring you regularly. You should see an improvement in your symptoms once your levels normalise.

If you are taking Amioderone for atrial fibrillation, get your thyroid levels checked regularly (at least every 3 months) to ensure that your thyroid is not being damaged by the medication.

What can you do about it?

Depending on the cause of your thyroid problem, it is important to try and reduce any causes that could worsen the problem. For example, ask your doctor if you can stop the Amioderone if that has caused the thyroid problem.

Optimising treatment is essential and once your levels are normalised, you should feel a lot better and your risk of heart problems reduce.

Treatment is not a ‘once size fits all’. Some people do well on synthetic thyroid replacement, others see no improvement. If you are still suffering symptoms then ask to be referred to an endocrinologist or gynaecologist who specialises in hormones.

Talk to your doctor

Talk to your doctor about other ways you can improve your thyroid function, but some things that have been shown to help include:

  • Avoiding gluten. If your thyroid problem is caused by an autoimmune condition then giving up gluten has been shown to help. There has also shown to be a link between those who are sensitive to gluten or Celiac and thyroid disease.
  • Avoid alcohol – although the occasional drink probably won’t cause any lasting thyroid problems, when consumed regularly, alcohol can become a serious health risk. Regularly drinking inhibits the thyroid hormones, free T3 and T4. Also, beer, wine and some spirits contain plant versions of the hormone oestrogen, known to trigger the human immune system. This might explain why some people with Hashimoto’s experience flare-ups in conjunction with drinking alcohol. Alcohol also prevents the immune system from defending itself against infections and inflammations in the body. Try reducing your intake and see if it helps.
  • Caffeine – Studies have found that drinking coffee at the same time or shortly after taking your Levothyroxine tablets can significantly lower the absorption of the thyroid medication in your intestines. The caffeine in coffee is believed to be the cause of this effect. Take your tablets at least 30 minutes before food or coffee.
  • Low stomach acid or Proton Pump Inhibitors (Omeprazole etc) – those with low stomach acid were found to absorb less of their Thyroxine. If possible, reduce the amount of PPI or take a small amount of lemon in water with your tablet on an empty stomach to improve absorption.

Make sure that you don’t put up with symptoms of a thyroid disorder. Keep going back to your doctor until they listen to you (or change your doctor!)

Want to know more about how thyroid affects the heart?