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Thyroid Myopathy from high dose?

Dr. Lupo,

I posted this same question on the patient community thyroid forum, thinking it was for your forum here. If I also get patient feedback on the other forum, that will be great too!

My question: Can "thyrotoxic myopathy" be induced by excessive dose of thyroid hormone replacement?

I posted previously in regard to my having been over-replaced with Armour thyroid, my T3 level being up to more than double highest normal (high normal 450 - my result over 900). As a result, I was reduced by a half-grain. I believe it's possible I've been over-treated for years, rather than months. I have been experiencing some muscle weakness for years but my doctors have also been keeping my TSH suppressed to near undetectable for all this time (i.e 0.005, due to my T4 being low-ish, compared to my T3. They would not add T3 level to my repeat bloodwork unless I requested repeatedly. I'm beginning to wonder if my myopathy is related to overdosing on Armour or that it is a 'contributing factor', since I am also being treated for vitamin deficiencies (D and E).

Thanks so much.
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Avatar universal
is armour better than synthroid for my athletic 15 year old son who was diagnosed with hashis thyroiditis?he had a cardiac ablation 5 months ago for wpw--but seems ok from that.a holistic dr wants the armour and a pediatric endo wants syntroid--what do you think?thanks alot
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Avatar universal
Thank you so much Dr. Lupo, that is exactly the type of info I needed, to share with my neurologist. I also wanted to request the muscle biopsy, which he also mentioned to me some weeks ago. This will help me to better discuss my case with him. I personally feel that both my vitamin E deficience (result 0.4 in a range of 3.0 to 15.8) and my over-treatment on thyroid hormone, have resulted in a combination of myopathy and neuropathy symptoms. With my only having been on E replacement for 2 months and my reduced thyroid hormone dose for only a couple or three weeks, both of these need more time to work. I feel this is common sense.

I really appreciate the help.
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97953 tn?1440865392
MEDICAL PROFESSIONAL
Too much thyroid hormone from any source can cause myopathy.  Muscle biopsy can sometimes help clarify that this is the cause and not something else.
Doubt it is peripheral resistance, it is not uncommon for patients to lack typical symptoms.

  From a thyroid medication standpoint, the key will be to get the levels normal and keep them there - it may take 6-12 months for muscles to recover if the myopathy is due to excess thyroid hormone.
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Avatar universal
Forgive me for adding this second part to the question but --- Could the fact that I didn't experience classic hyperthyroid symptoms after severe over-dosing by my GP on Armour, indicate Peripheral Thyroid Hormone Resistance (myopathy being lack of thyroid hormone in my tissues)?

My neurologist (not the Dr. who is dosing my thyroid) is looking into all possibilities, including referring me to muscle specialist or a thyroid one, etc..., so I will be printing off your reply for supplying to him.

Thanks again.
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