What Hypothyroidism Does To Your Heart

Hypothyroidism affects 4–7% of the population, but most goes undiagnosed.

If you’re a woman, you’re 11–15% more likely to have it than if you’re a man.

The epidemiology of this is interesting, but not our main topic today, so if you’d like to read more about that, then you might want to bookmark this paper to read later: Low awareness and under-diagnosis of hypothyroidism

If you’re wondering if this might be you, then check out: Doctor Explains: 15 Signs Of Hypothyroidism

And perhaps, while you’re at it, A Fresh Take On Hypothyroidism← she also recommends getting tested for T3 levels, which often isn’t standard, as many providers just to TSH testing as a proxy, rather than testing thyroid hormone levels directly, and THS tests aren’t a reliable marker of thyroid function, especially if you have Hashimoto’s. Further, she notes that many prescribed drugs that are actually pro-drugs*, that don’t get converted adequately if you have an underactive thyroid.

^{*a “pro-drug” sounds exciting, but it’s just what it’s called when the drug we take is not the actual drug the body needs, but is a precursor that will get converted to that actual drug we need, inside our body—usually by the liver, but not always. An example in this case is T4, which by definition is a pro-drug and won’t always get correctly converted to the T3 that a thyroid patient needs.}

We also covered some new research on this quite recently, here: What You’re Probably Still Missing In Hypothyroidism Treatment

Meanwhile, what’s this about hypothyroidism and your heart?

Let’s get to the heart of things

Researchers (Dr. Irsa Munir et al.) analyzed 112 ICU patients with hypothyroidism using transthoracic echocardiography and speckle-tracking echocardiography, including patients with myxedema coma.

That’s a lot of big words, but a fair oversimplification would be: they used low- and high-tech means to monitor cardiac function in various ways.

What they found is that hypothyroidism was strongly associated with measurable heart dysfunction, which makes it look a lot like low thyroid hormone levels can directly impair how well the heart contracts and relaxes.

In numbers:

• 66.7% had abnormal diastolic function
• 68.2% had impaired left ventricular global longitudinal strain
• 37.5% had reduced left ventricular ejection fraction
• 34.0% had impaired right ventricular strain

You might be wondering: why are we assuming causality?

And the answer is: thyroid hormones help regulate your heart’s response to adrenaline, energy use, blood vessel tone, and the timing and force of contraction, so deficiency can weaken cardiac performance.

Notably, cardiac abnormalities occurred at similar rates in patients with and without overt myxedema coma, indicating that hypothyroidism itself (not only the coma state) was linked to dysfunction.

Another factor that Dr. Munir and her team highlighted is that of the various thyroid hormones, low T3 levels are common in septic shock and raised the possibility that prolonged thyroid hormone deficiency can contribute to septic cardiomyopathy.

You can read the paper in full, here: Heart ventricular function in hospitalized patients with severe hypothyroidism and myxedema coma

As for what to do about it? Their preliminary lab work strongly suggested thyroid hormones can improve cardiac muscle contractility within minutes, and a clinical trial protocol has been approved to test hormone replacement in septic shock patients, so we’ll look forward to seeing that when it comes out.

In the meantime, there has a been a lot of other new research about this published in the past few weeks (at time of writing), for example:

• Cardiac myxoedema due to severe hypothyroidism mimicking myopericarditis
• Differential association of hypothyroidism with cardiovascular events and cardiovascular mortality: a systematic review and meta-analysis
• Association of inadequately controlled hypothyroidism with major adverse cardiovascular events in type 2 diabetes patients receiving levothyroxine

Aside from treating it with thyroid hormones directly, this problem is also often approached from the perspective of “can we fix it with diet?”, and indeed, there are prevailing methods for at least managing the condition, for example: Foods For Managing Hypothyroidism (incl. Hashimoto’s)

However, regular 10almonds readers may remember we wrote about an approach that evidence suggests is not only stronger, but also much easier to adhere to in real life with real life’s practicalities: No More Restrictions In This Diet Against Thyroid Disease?

Want to learn more?

If you’d like to read more about a common form of hypothyroidism, then check out:

Hashimoto’s Food Pharmacology – by Dr. Izabella Wentz

Take care!