Thyroid News: High fT4 May Increase Risk of SCD (Sudden Cardiac Death)


The Heart and Thyroid Connection

Hey people!

In the last few days there’s been lots of news coverage of the influence of thyroid hormone and thyroid hormone levels on the heart. All of these news outlets had stories:

CBS News


Science World Report

Clinical Endocrinology News

This is all because of a new study out of the Netherlands in a medical journal called Circulation. The study found that elevated levels of free T4 may result in an increased risk (1%-4%) of sudden cardiac death, even in normal patients.

When asked why, the theory was that “Our hypothesis was that thyroid hormone levels could increase the risk of sudden cardiac death by affecting cardiovascular risk factors such as blood pressure levels,” said Dr. Layal Chaker, research fellow in endocrinology and epidemiology at Erasmus University Medical Center Rotterdam in the Netherlands, lead author of the study.

I’ve done a bunch of research on this area and I covered it in my book, Roadmap to Remission. One thing I discovered was that the heart is very sensitive to thyroid hormone, especially T3.

This is an excerpt 9IN ITALICS) from the section on the Fire Element, which includes the cardiovascular system. It includes a good, easy to understand explanation for exactly what might cause all of this to happen.

The Heart

The heart circulates nutrients by pumping blood throughout the body.

When blood is pumped through your body, it puts pressure against the walls of your blood vessels.

Right? This is your blood pressure.

When doctors describe blood pressure, they use two numbers like “120 over 70”. These numbers describe the pressure when your heart pumps blood into your blood vessels (the high number) and the pressure when your heart relaxes (the low number).

Imagine squeezing a ketchup bottle. When you squeeze it to ‘pump’ ketchup onto your plate, the pressure is high. When you stop squeezing, the pressure is low.

Blood pressure can change a lot during the day. It is usually lower while you are relaxing and higher when you are active. Other things like pregnancy, smoking, medication, being stressed and thyroid hormone levels can change your blood pressure.

Hypothyroid, But High Blood Pressure?

Usually, with hypothyroid conditions, you’re blood pressure is low and with hyperthyroid conditions it tends to be high. But there are many reasons why this is not always the case, in fact, many Hashimoto’s people actually have high blood pressure.

This is because even though many thyroid patients, or those being treated with T4 meds like Synthroid, can start out with low blood pressure, factors related to having functional hypothyroidism can actually create hypertension and high blood pressure over time.

For example, as we saw when we looked at the Water Element hypothyroidism leads to a host of problems physiologically that cause kidney and cardiovascular problems.

For example, there’s less blood flow to the kidneys, this causes the kidneys to not filter waste products like creatinine from your body properly.

In addition, when your blood pressure is low, and “angiotensin” is produced, this raises your blood pressure.

Also when you are hypothyroid, blood is taken from the extremities into the body, which tends to raise pressure by forcing the same volume of blood into a smaller network of vessels.

This process is brought about by a constriction of peripheral vessels.

Hypothyroid patients produce an excess of noradrenalin from the adrenal gland, which constricts blood vessels all over the body, another effort of the body to deal with the low blood pressure.

This in turn is partly related to the effort by the body to raise blood sugar levels when low. We’ve already discussed this, as well.

These problems may or may not be caused by being overmedicated.

Anxiety, tachycardia (fast heart rate), and high blood pressure that people with Hashimoto’s experience is not always from being hyperthyroid or overmedicated, it may also be from noradrenaline that the body is secreting for energy to compensate for the lack of thyroid hormone.

Unfortunately, what often happens is that they’re prescribed blood pressure medications (such as beta blockers) and/or anti-anxiety medications (such as benzodiazepines).

Neither of these drugs corrects the underlying functional hypothyroidism (low thyroid condition) that caused the symptoms in the first place, and both have side effects. In one study, noradrenaline was three times higher in hypothyroid subjects than normal controls when lying down.

So what was once low blood pressure, now takes a nasty turn towards hypertension, or high blood pressure.

Another….you guessed it, vicious cycle.

Obviously, too high blood pressure can be dangerous. It means that there is too much stress on your blood vessels. This makes the vessels weak and can damage them. Imagine squeezing a ketchup bottle really hard and fast until it breaks.

High blood pressure is a major cause of heart disease.

How the Thyroid Impacts Cardiovascular Function

Ok, so let’s take a look at how else the thyroid impacts cardiovascular function. Firstly, thyroid hormone has a direct impact on cholesterol; with hypothyroidism serum cholesterol increases.

Thyroid hormone stimulates an enzyme called HMG-CoA reductase, the same enzyme that statin drugs inhibit. This speeds up the synthesis and utilization of cholesterol by the body.

Thyroid hormone stimulates the removal of cholesterol by the liver using LDL receptors. In a hypothyroid state, this whole process is slowed and the result is that cholesterol builds up and isn’t cleared as quickly.

Hypothryoidism can also cause homocysteine levels to rise. High homocysteine can lead to inflammation of the arteries and can make you more prone to blood clots, heart attacks and strokes.

We talked about that in the last chapter too, because nourishing certain pathways in the liver can really help bring down high homocysteine.

CRP, another risk factor and inflammatory marker for inflammation in the arteries is also often high with hypothyroidism.

Another odd thing that too little thyroid hormone can cause is lower plasma volume. This is caused by capillaries becoming more permeable and when this happens albumin and water leak into the interstitial spaces.

So here again, we have the makings of a particular dangerous vicious cycle.

In the chapter on the Earth Element, we spoke about how blood sugar problems like metabolic syndrome can create a lot of conditions that make you more likely to develop heart disease.

Well, when you combine that with hypothyroidism, you have a very potent combination that can put you at risk for heart attack and stroke.

Thyroid Hormone and The Heart

Another area that does not get the attention it deserves is the impact of thyroid hormone on the heart and cardiac tissue. One of the things that research is starting to reveal is that thyroid hormone is absorbed differently by different tissues of the body.

In other words not every part of you body is affected the same way by T4 and T3. For example, the pituitary is different than every cell in the body with different deiodinase enzymes and it has more sensitive to thyroid hormone receptors.

Many physicans assume, incorrectly, that thyroid hormone is simply absorbed via diffusion (which is basically like the cell sucking hormone in through a biochemical straw).

However the reality is that the process is energy dependent and called active transport which means it requires the body to use energy to push it into the cells.

In addition, different parts of the body respond differently to T3 and T4. 90% of T3 is absorbed by the stomach while T4 is much less efficient (50 – 90%) and T4 requires much more energy to get absorbed.

T3 affects cardiac muscle cell (myocyte), it affects contraction, T3 also affects the performance of sodium, potassium and calcium channels in the heart.

And what this new study concluded was that “Higher FT4 levels are associated with an increased risk of SCD (sudden cardiac death), even in euthyroid (normal thyroid) participants.” This was an increased risk of 1% – 4%, so don’t panic, that’s not a huge increase. 

What this means is that just throwing more thyroid hormone at the problem may not be the answer and can have unintended consequences.

And something else the research has identified is that thyroid autoimmunity can affect the valves of the heart. So, if you have Hashimoto’s and have been diagnosed with heart murmur, an echocardiogram might be a really good idea.

Way More Than A Thyroid Problem

What this also tells us that this is way more than a thyroid problem and issues in other systems of the body must be treated, as well.

And where your heart is concerned it’s super important to take steps to reduce all the risk factors that contribute to cardiovascular disease. And sugar, inflammation and lack of exercise are the big three that put you at risk.

It’s all connected people!

Everything we do or don’t do has consequences. Properly managing and treating your thyroid may also heal your heart and properly managing and treating heart disease may also heal your thyroid.

Not sure what to do? Set up a consult and we’ll discuss how to create a heart healthy program for you.

Book a 30 minute Consultation.

About the Author Marc Ryan

So now, not only is it my profession, it’s my passion, and it’s personal. I’ve been joking with people lately saying it’s a blessing and a curse. A blessing because I really get it, and a curse because I really got it! ?

follow me on:

Leave a Comment: