High dose T3 and muscle loss: Hi- I am currently... - Thyroid UK

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High dose T3 and muscle loss


Hi- I am currently on 200mcg T3. I have been on 125-250, but am now on 200. This is prescribed by a doctor in the US. I want to decrease further as sometimes my heart rate is a little high (however when I decrease even by 10 I have horrible hypo symptoms).

I have noticed in the last year I have lost ALL MY MUSCLE MASS. I used to be really athletic, with approx 16% body fat. I now have 36% body fat even though my weight is the same (DEXA test so 100% accurate). Devastated. It look awful. My body is so saggy. I’m 46 (female). Has anyone experienced this? What can be done?

Very very sad.

3 Replies


Wow .... what a high dose of T3 you are medicating. Have you got tissue resistance or something ?

T3 increases all aspects of protein synthesis in the muscles allowing growth to occur. It gives us energy, which allows exercise, which stimulates protein synthesis, which when greater than the amount of protein broken down results in longer leaner muscle growth.

Many hormones work together as a team to influence muscular growth & adrenal glucocorticoids such as cortisol (stress hormone) is responsible for protein breakdown. But in a previous post you indicated elevated DHEA which usually accompanies low cortisol levels and because your muscle wastage appears quite drastic, I think it to do with not be able to consume enough protein to match the amount of T3 you are medicating.

Thyroid hormone drives our metabolism and as such dictates protein turn over rate. The body makes some and we need to eat a fair proportion that is digested into amino acids, and re-assembled into long chains called proteins. Think of body builders who supplement protein.

Also be aware that amount of T3 could be encouraging more bone absorption than bone production with a net loss of bone mass. What did the DEXA show your bone density to be ?

Also, elevated T3 levels can cause SHBG to rise which could bind to thyroid hormone making it inactive. Have you had this measured ?

in reply to radd

Wow Radd, what I would do to meet you.

My SBHG is very very elevated.

My bone density so far looks ok.

What would you do? Should I decrease my T3? When I have tried to do that in the past, I have gained weight very rapidly, and I really really don’t want that to happen.

I’m not sure I understand exactly what is happening but it sounds like I’m over medicated, is that what you are saying?

What does it mean if SBHG is very elevated? Does this mean that the T3 I am taking in not working?

I eat roughly 140-160 grams of protein a day. I’m very careful with my diet, lots of healthy fats etc...

I don’t really understand the SBHG issue (or low cortisol/DHEA)... could you possibly explain further? It sounds like you are sayin that the more I take the more SHBG will rise to ‘eliminate’ it.

My doctor wants me on more but honestly I’m trying to take less (the numbers scare me), but I am so anxious about gaining weight (I can’t for my job).

Can anyone elaborate on high SBGH levels binding to thyroid hormone? Thank you!

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