Thyroid UK
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Advice on T4 /T3 dosage

I saw the very new doc yesterday and my blood test results were in. Happy to see my good feeling was mirrored in the results ( thus no need to defend my T3-only regime).

T3 5.1 (2.6-5.7); T4 6.6 ( 9.0-19.1); TSH 0.24 ( 0.35-4.94).

My ferritin was up, B12 looking good, Vit D could be much better. Blood pressure really high though and cholesterol up and for the first time ever triglycerides. That was disappointing.

He said he was happy for me to continue with my T3 but would prefer me to be on T4. I had already decided however that I would try T4/T3 again, if only because I am probably a marked woman as far as customs are concerned so re-ordering T3 from Greece could end in tears. Expensive ones and the threat of legal action, apparently.

I know too that T3/T4 combo is available here at 20/100mcg...

In the meantime, could someone give me advice on dose equivalents? I have been taking 50/62.50mcg T3 split into 2 or 3.

Would 25mcg T3 and 100mcg T4 be the correct equivalent? Should I take less T4 and more T3 to avoid any shock to the body seems pretty content at the moment.

Doc thinks I will be dropping T3 for 50mcg of T4. He didn't ask what dosage of T3 I have been on so it was obvious he was floundering a bit. No matter. We seem to have an understanding.

Many thanks indeed for your help.

2 Replies


T3 is 3 x stronger than T4 so 60mcg T3 is equivalent to 180mcg T4. 100mcg T4 + 25mcg T3 is equivalent to 175mcg T4 so seems a good starting point.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

1 like

Many thanks Clutter.


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