Episode - Muscle Weakness and Hyperthyroidism


Muscle Weakness and Hyperthyroidism

If you’re experiencing muscle weakness or decreased muscle mass, there’s a good chance it’s related to your hyperthyroidism. At the same time, knowing that other causes might be at play is essential.

After I was diagnosed with Graves’ disease, I experienced a noticeable loss of muscle mass associated with hyperthyroidism. Years later, I was walking with my daughter, and one of my legs started giving out. That was the first time I’ve ever experienced something like that, and it turned out to be a symptom of chronic Lyme disease.

I can’t emphasize this enough: you always want to identify and address the root cause of your symptoms.

Today I’m talking about the connection between muscle weakness and hyperthyroidism, exploring other causes such as electrolyte imbalances, medications, and infections, how to test for decreased muscle mass, what you can do to address the cause of your symptoms, and more.


During this episode, you’ll learn about:

  • Low creatinine levels are associated with lower muscle mass
  • Decreased muscle mass and muscle weakness are associated with hyperthyroidism
  • The role of thyroid hormones in sarcopenia
  • My experience with decreased muscle mass and muscle weakness
  • Addressing the cause of the problem is key
  • Hyperthyroidism may influence the clinical course of myasthenia gravis
  • What the research around muscle weakness and hyperthyroidism shows
  • Medications, infections, and other issues associated with muscle weakness
  • Methods for normalizing thyroid hormone levels
  • Addressing other potential causes of muscle weakness
  • What you can do to increase muscle mass
  • Figuring out how much protein you should eat


Click Here to read the research study I mentioned during the episode


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Here is the transcript for this episode:

Welcome back to the Save My Thyroid podcast. This is Dr. Eric Osansky, and in this episode, I am going to talk about muscle weakness and hyperthyroidism. Even though this presentation is focusing on people with hyperthyroidism, of course people with hypothyroidism can experience muscle weakness.

I wanted to mention that decreased muscle mass is very common in those with hyperthyroidism. When doing blood testing, there is a panel called the comprehensive metabolic panel. There is a marker called creatinine. Usually, those with hyperthyroidism, especially if the hormone levels are very high, these creatinine levels will be on the lower side and sometimes overtly depressed. That is related to muscle mass. Of course, many times you don’t have to see low creatinine levels to see you have lower muscle mass because you can tell without looking at a test.

Muscle weakness can also be related to hyperthyroidism as well, but it could be other causes. Same is true with decreased muscle mass.

I want to briefly talk about sarcopenia. Sarcopenia is the age-related loss of muscle mass along with strength and quality. Thyroid hormone can cause a transition from a slower fiber type to a faster one. This could play a role in sarcopenia. Skeletal muscle quality relies on the health of the mitochondria. This in turn is modulated by T3, which is one of the thyroid hormones.

As far as my experience with decreased muscle mass, when I dealt with Graves’ I definitely experienced a loss of muscle mass. In 2008, I was diagnosed with Graves’. In 2018, I was diagnosed with chronic Lyme disease. In that case, I didn’t have decreased muscle mass, but I did experience muscle weakness. In fact, that was one of the major symptoms I noticed, which led me to see a Lyme specialist and get diagnosed. I was walking with my daughter, and one of my legs started giving out. It was the first time I ever experienced something like that.

Some people with hyperthyroidism experience both loss of muscle mass and muscle weakness. In many cases, resolving the hyperthyroidism is the key. Even though you need to resolve the hyperthyroidism, if you have that decrease in muscle mass, you will probably need to do things to increase the muscle mass, whether it’s weight-bearing exercises and/or increasing your protein intake. Of course, you want to resolve the hyperthyroidism because if you don’t address the cause of the problem, then you will continue to have that decreased muscle mass.

I want to briefly mention myasthenia gravis in relation to hyperthyroidism. Hyperthyroidism occurs in approximately 2-17.5% of patients with myasthenia gravis. This is a chronic autoimmune disorder in which antibodies destroy the communication between nerves and muscle. This results in weakness of the skeletal muscles. Hyperthyroidism may influence the clinical course of myasthenia gravis. There is that relationship, but it’s safe to say that most people with hyperthyroidism who have muscle weakness do not have myasthenia gravis. Since myasthenia gravis is an autoimmune condition, as is Graves’, and if someone has one autoimmune condition, they are more likely to develop other autoimmune conditions. We need to keep this in mind.

Now I’d like to discuss a little bit of the research when it comes to muscle weakness and hyperthyroidism. There was one study that demonstrated the degree of muscle weakness in newly diagnosed Graves’ patients and to assess their response to treatment. The results showed that muscle weakness is commonly associated with hyperthyroidism and in some cases can be quite profound.

It also showed the beta blocker propranolol, which some folks are given with hyperthyroidism. Propranolol is commonly given because it affects the conversion of T4 to T3. The studies showed that propranolol can improve muscle weakness in people with hyperthyroidism. It’s a little bit puzzling that they didn’t use antithyroid medication, but perhaps it’s because methimazole and PTU, which are the more common types of antithyroid medication, commonly cause side effects. As I mentioned before, propranolol can negatively affect the conversion of T4 to T3, so it can reduce those T3 levels. I’m sure if they did a trial with antithyroid medication, they would also have proven that muscle weakness would have been decreased.

Of course, there can be other causes of muscle weakness. There is a good chance that the experience of muscle mass decrease and muscle weakness is related to the hyperthyroidism, but it could also be sometimes another cause. There are electrolyte imbalances. Certain medications can also cause muscle weakness, including statins, which is commonly given for high cholesterol levels; glucocorticoids; and fluroquinolones.

Certain infections, like Lyme disease or other infections. Viruses such as West Nile, HIV, Hepatitis C, cytomegalovirus, herpes, and many other viruses, like diphtheria, Dengue fever, trichinosis, botulism. I don’t want to say any type of infection can cause muscle weakness, but keep in mind that many different types of infections can cause it.

There are other causes like amyotrophic lateral sclerosis (ALS), which is also known as Lou Gehrig’s disease. Having a cerebral lesion, such as a stroke. Compressive neuropathy of the peripheral nerves. Motor neuropathy. Multiple sclerosis. Adrenal insufficiency. When it’s really severe, it’s known as Addison’s Disease. There is also Cushing syndrome. Muscular dystrophy.

How do you overcome muscle weakness? Of course, you need to address the cause of the problem. If someone has hyperthyroidism, it’s important to lower thyroid hormone levels. If you have hypothyroidism, you want to normalize hormone levels. If someone has hyperthyroidism, they may take antithyroid medication and/or a beta blocker on a temporary basis. There are natural agents, like bugleweed, which I took, an herb that can help lower thyroid hormone levels.

You want to address other potential causes of muscle weakness. If you have an underlying infection, you may not know it’s there. If you have an overt infection, you want to address it. If someone has reduced muscle mass and/or muscle weakness, not only does the underlying cause need to be addressed, but some weight-bearing exercises probably will be necessary. You will need to do things to get the muscle mass back. If it’s decreased, it won’t come back on its own. Over time, you will gain some muscle mass, but you do want to assist with this process.

Let’s summarize. Muscle weakness can be a factor in hyperthyroidism or hypothyroidism, but there can be other causes as well, such as electrolyte imbalances, certain medications, certain infections, and others. Decreased muscle mass is very common in those with hyperthyroidism as well. You can look at a comprehensive metabolic panel, and low creatinine levels is usually an indication of lower muscle mass. Once again, most people don’t need to look at that to know they are experiencing muscle mass issues. Either way, you need to address the cause. If the muscle mass is decreased, you might need to increase the muscle mass, such as through weight-bearing exercises.

This wraps up my presentation on muscle mass and hyperthyroidism. I hope you found this episode to be super valuable, and I look forward to catching you in the next episode.