Tachycardia and Hyperthyroidism
It’s very common for people with hyperthyroidism to experience tachycardia, which is an elevated resting heart rate. And while the elevated thyroid hormone levels are what cause the heart rate to be high, there can be other factors, which will be discussed in this episode, along with things you can do to address this condition.
During this episode you’ll learn:
- Different causes of tachycardia (besides hyperthyroidism)
- The three types of tachycardia, including the type most commonly associated with hyperthyroidism
- Potential causes of unmanaged tachycardia
- How to manage an elevated resting heart rate
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Here is the transcript for this episode:
Welcome back to the Save My Thyroid podcast. This is Dr. Eric Osansky. In this episode, I am going to discuss the relationship between tachycardia and hyperthyroidism. Let’s goa ahead and start by discussing what tachycardia is. Most sources consider a resting heart rate over 100 beats per minute as being tachycardia. I personally prefer to see the resting heart rate less than 80 beats per minute. I would be concerned with a resting heart rate of 90 beats per minute or higher. Ideally, you want a resting heart rate in the 50s or 60s for those in a good state of health. Low 70s is still acceptable. A lower resting heart rate usually indicates a higher level of cardiovascular fitness.
I’d like to discuss the different types of tachycardia. There are three types. Type one is atrial or supraventricular tachycardia. This involves an irregular heart rhythm also known as an arrhythmia. This starts in the upper chambers of the heart.
The second type of tachycardia is sinus tachycardia. This is a regular heart rhythm that is faster than normal and results in an increasing cardiac output. This is the type of tachycardia most commonly associated with hyperthyroidism.
The third type is called ventricular tachycardia. This involves an arrhythmia that starts in the lower chambers of the heart.
Let’s discuss some of the common causes of tachycardia. Hyperthyroidism is definitely a common cause, especially in my patient base since many of my patients have hyperthyroidism. Whether someone has Graves’ or toxic multinodular goiter or subacute thyroiditis, most of these people will have an elevated resting heart rate.
There can be other causes, too, even in people who have hyperthyroidism. I do have patients who have an elevated hormone level responsible for tachycardia, but sometimes the thyroid hormone levels normalize because they are taking methimazole or bugleweed, yet they are still experiencing tachycardia. It could be related to some of these other causes:
- Elevated cortisol levels are a common cause. Some people have low cortisol levels, which was the case with me when I had Graves’. A lot of my patients have high cortisol levels though.
- Dehydration, not drinking enough water.
- Hyperkalemia, which is elevated potassium levels.
- Low magnesium
- Hypocalcemia, which is low calcium.
- Certain infections, like viral infections or different types of bacterial infections
- Postural Orthostatic Tachycardia Syndrome (POTS). This is a condition found in the autonomic nervous system. It’s characterized by symptoms of lightheadedness, fatigue, palpitations, sleep disturbances, cognitive impairment, and brain fog. It involves an increasing heart rate when upright even though the blood pressure remains normal.
- Certain medications. Examples include albuterol, amphetamines, antihistamines, clozapine, dobutamine, ephedrine, and levothyroxine. For instance, if someone has Hashimoto’s, if they are taking a normal amount of thyroid hormone replacement, they should be fine. But if someone is taking higher amounts of levothyroxine or desiccated thyroid hormone, that definitely can cause tachycardia. Theophylline and tricyclic antidepressants are two more.
- Histamine intolerance. I actually left this out of the episode, which I realized when I recorded a separate episode on histamine intolerance. But some of the symptoms of a histamine intolerance can mimic those of hyperthyroidism, including tachycardia.
I’d now like to mention some potential consequences of unmanaged tachycardia:
- Myocardial ischemia
- Low blood pressure
- Low cardiac output
- Peripheral hypoperfusion, a reduced amount of blood flow
- Tachycardia mediated cardiomyopathy
- In rare cases, cardiac arrest, and even death, when that resting heart rate becomes extremely high for a prolonged period of time
The good news is that most of these conditions are partially or completely reversible.
Let’s discuss the management of tachycardia. From a conventional medical standpoint, many times, they will give beta blockers or what’s called angiotensin converting enzyme inhibitors. If someone has hyperthyroidism, typically they will be given antithyroid medication such as methimazole or PTU. This will lower the thyroid hormone levels and most of the time will help greatly with the tachycardia.
There are also natural methods like motherwort, which is an herb that I think of as a natural beta blocker focusing on the cardiovascular system. There is hawthorn, which also focuses on the cardiovascular system. There is bugleweed, an antithyroid herb, which is what I took when I dealt with Graves’, and it helped with my tachycardia. It doesn’t work with everyone, so keep that in mind, but it works in about 70% of people that take it.
Of course, you want to try to address the cause of the tachycardia. I just mentioned some ways to manage the symptoms. If someone has hyperthyroidism, and they take bugleweed or antithyroid medication, while it’s important to do this to lower the resting heart rate because you want to be safe, at the same time hopefully you’re doing things to address the cause of the problem. Most endocrinologists will recommend radioactive iodine or thyroid surgery as their permanent solution. As you know, I am going to recommend trying to find the triggers and other underlying imbalances to address the cause of the problem.
Management of tachycardia is definitely important. Especially if someone has a resting heart rate in the triple digits, you need to get that down. While doing that, you want to address the cause of the problem.
Let’s go ahead and summarize this episode. Most sources consider a resting heart rate over 100 beats per minute as being tachycardia. There are three different types of tachycardia that I discussed with sinus tachycardia the most commonly associated with hyperthyroidism. There are many different causes of tachycardia. There are risks of unmanaged tachycardia. Tachycardia can be managed in numerous ways, including by taking beta blockers; antithyroid medication; or herbs such as motherwort, hawthorn, or bugleweed. But as I mentioned, you always want to try to address the cause of the problem. In my situation, I deal with a lot of people with hyperthyroidism, so my goal is not to just have the person take bugleweed or motherwort if they are taking an herbal approach or antithyroid medication. Whatever the situation, you want to always address the cause of the tachycardia.
That’s all I want to discuss when it comes to tachycardia. I hope you found this information to be valuable. I look forward to catching you in the next episode.