Muscle Weakness is both a Hyperthyroid and Hypothyroid Symptom

Muscles need thyroid hormone to function correctly, and either too much or too little thyroid hormone can cause muscle weakness and pain. If you are taking thyroid hormone and recent labs show your T3 and/or T4 levels already on the high side, your muscle weakness may be due to too much, not too little thyroid hormone.

In hyperthyroidism, the excess thyroid hormone literally eats up muscles, and it’s referred to as muscle wasting. Muscle protein breakdown and decreased muscle mass is measurable in Graves’ hyperthyroid patients. It is most apparent in the upper arms and thighs, and muscle testing will show decreased muscle strength. Abnormal measurements of muscle protein breakdown normalized after treatment brought thyroid levels down.

Hypothyroid patients also complain of muscle weakness, but this is from lack of thyroid energy, not actual muscle breakdown. Hypothyroid patients complain of paresthesia (tingling, like pins and needles), carpal tunnel syndrome, and peripheral neuropathy (weakness, numbness, or pain, usually in the hands or feet). In one study, 70% of the hypothyroid patients had abnormal electromyograms, which measure the electrical activity of muscles (at rest and during contraction).

I would describe hypo muscle weakness as more like a lack of muscle stamina. The muscles suffer from the same fatigue that the person feels. My left foot would “buzz” when my dose was too low. But I could certainly climb stairs and hold things above my head—though I felt tired doing anything. Hyper muscle weakness is much more severe, and legs and arms may tremble doing simple things, like holding your arms up to shampoo your hair, or getting up from a chair.  That is definitely a sign that something’s wrong, and your dose needs to be reevaluated. More is not always better, and the best advice I ever read (from a Graves’ patient) was: if you don’t feel better raising your dose, try lowering it instead.

10 thoughts on “Muscle Weakness is both a Hyperthyroid and Hypothyroid Symptom

  1. Thank you for this. I used to think being a little hyperthyroid was a good thing until I saw what it did to my muscles…

  2. Can Graves’ disease leave permanent damage to muscles? I am post TT nearly 3 years, but started having extreme low back pain and spasms after i was diagnosed with Graves’ and had already began anti-thyroid meds, block and replace. That was over 3 and half years ago and i have had this back problem since, also affects my leg and hips now.

    • I don’t know if the damage is permanent, but as stated in the article, both too little and too much thyroid hormone can cause all kinds of aches and pains. People on anti-thyroid meds sometimes become quite hypo. Were you taking enough replacement then and now? Are you taking at least some form of T3? I’ve heard of others in pain who improved once they got their thyroid levels, both T4 and T3, more optimal.

  3. I have been diagnosed with possible hypothyroidism. I have noticed my thighs have lost a lot of muscle on both sides is this normal?

    • Well thyroid isn’t the only hormone used by muscles. Testosterone ranks right up there too. I would get comprehensive lab tests to see where your deficiencies are.

  4. Aaron

    I am also sub clinical hypothyroid. Not every problem is due to your thyroid hormones. It is more probable your muscle wasting on both side is from insulin resistance or II diabetes. Drinking too much alcohol has the same effect of some people.

  5. I am hypothyroid caused by hashimoto’s. I am 35 year old female. I suffer from muscle wasting also. I am now on levo for 3 years and my Tsh is at 0.95. Which my endo says is perfect? But I am still having muscle loss. I excercise daily and take vitamins, minerals and drink a protein shake daily, but I still cannot gain any muscle mass! What other things for a female can cause actual loss of muscle, not muscle weakness? Thank you in advance…. Also.. throughout me being hypo, I suffered weight loss, not weight gain. Is this normal. On the levo, I still keep losing weight. I eat alot, but nothing. I feel as though I am literally wasting away…

  6. I just got diagnosed with hypertyroidism and i feel like my legs start shaking and a severe loss of strength and muscle. I am taking methimazole and proponolol is there any way i could regain my strenght..what do yall recommend thanks

  7. I was diagnosed with hypertyriod I’m not sleeping in the night my hair drop out I feel weak and fatigue lost weight mussels pain in the night but I started talking magnesium and propane nolo the pain ease up

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