Optimal FREE T3 range science

Hi All,

I have read that the optimal FT3 range should be in the top 25th percental of the "normal range".

I've just had my FT3 tested, it comes up as 4.5 pmol/l with the lab range of 3.5 - 6.5. Doc, of course, says it's normal, but it is not in the top 25th percentile. So I'm concerned that it's too low, (it works out as about 2.9 pg/mL)

Can anyone point me to some scientific articles of why my FT3 needs to be in the top 25th percentile that I can show my doc? I'm pretty sure he'll ignore all the articles I've found so far.



Senior Member
Old post but. ....some people feel okay with t3 over the half way mark (your half way is 5 ). Some patients have to get t3 to top of range to feel okay.
It really depends on quality of life and symptoms.
To rationalise dosing based on symptoms you need a doc that is open to it.
Or like thousands of others , you take it into your own hands and experiment.
There are studies out there that make a case for t3 levels but doctors have a set of best practice guidelines with steps for treatment that they adhere to.
T3 levels can fluctuate so it's best to have a few tests and check other thyroid markers as well.
How are you now?