conversion rates

I'm due to see my specialist tomorrow and would appreciate some advise.

I recently wrote a post about my medication being lowered due to my results and feeling symptoms return after lowering them to t3 10mcg/t4 75mcg from t3 10mcg/t4 125mcg.

I started back on the higher dose and feel so much better! I was wondering if the endo could still refuse to keep me on my current dose when he has told me to lower it.

Are conversion rates something I can take with me? I have read that even though my results show I'm on the upper end, this is where I need to be to function. I have put them into a calculator I found on here but I still don't really understand what it means? Can anyone help me put my case together to keep on my current dose, I need to feel confident and understand what I'm saying so I don't get talked into lowering it again.

My last results were:

Serum free T4 level18.1 pmol/L9 - 22.7pmol/L

Serum free T3 level6.5 pmol/L3.5 - 6.5pmol/L

Any advice would be much appreciated :)

10 Replies

Your Endo probably only looked at the TSH and adjusted your meds. The TSH is nothing to do with the thyroid gland as it is from the Pituitary Gland which rises if we are hypo. They should really ignore it when on thyroid hormones as it would stop them adjusting the dose unnecessarily as they have some mistaken information that we may get a heart attack if TSH is too low. Your FT4 and FT3 are good. so why mess about with adjustments of the TSH.

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I see… This is something i can bring up tomorrow, very helpful thank you :)


What dose were you taking when those blood results were done?

My dose was 125mcg T4 and 10mcg T3 at the time of the results, after this i lowered it to 75mcg T4 (T3 kept the same) I felt dreadful!


Your FT4 and FT3 weren't over range on 125mcg T4 + 10mcg T3 so I don't see why it had to be reduced especially as much as 50mcg. I suspect your TSH was suppressed and that may be why your endo reduced dose. If endo won't sanction 125mcg T4 + 10mcg T3 try to negotiate 100mcg T4 + 10mcg T3.

I'm not sure conversion has anything to do with it - and I don't know what you mean by 'conversion rates' - or what calculator you're talking about. The only way you can know how well you are converting, is by comparing your FT4 with your FT3, when you are on T4 only. There's no way you can tell how well you convert when taking T4+T3. :)

Lojosmelia_83 I think you may be talking about good conversion takes place when FT4: FT3 ratio is 4:1 or less. That applies when on Levo only, Greygoose is correct in that when on a combo of T4 and T3 then conversion doesn't come into it. I imagine your endo added T3 because originally you weren't converting very well, that can't be measured when taking T3.

I understand now, the T3 converts the T4, so the conversion calculation is irrelevant. Takes me a while lol! So for me, its all about how i feel regardless of my results then?

Lojosmelia_83 No, some of the T4 converts to T3.

T4 is a pro hormone, it is inactive. T3 is the active hormone which every cell in our body needs.

Lojosmelia_83 Forgot to answer your question - it is mainly about how you feel. TSH is irrelevant when on replacement thyroid hormone and adding T3 can suppress it anyway, FT4 often lowers when taking T3 and FT3 tends to increase. FT3 is the only important result really, however, it should stay within range.

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