pubmed.ncbi.nlm.nih.gov/248...
Hi I thought it was just the T3 in the cells that produced oxygen consumption and glucose uptake but according to this paper it is both the T4 and T3 in the cells which do it. I didn't know this. So obviously T4 is just as important as T3. Is this correct?
Interesting question - will watch out for Replies and thoughts ! Thank you for posting.
For folks with a dodgy thyroid, the importance of t4 will depend on the individual. For some the body has adapted to work with high levels of t3 and very low levels of t4. You will find folks on here who are on t3 only so for them t4 levels are not significant. For those on Combo t4/t3 each individual has to discover how important t4 is for them personally. For example with a Ft3 reading 74% through range and a ft4 reading 0% through range I am ill and have no voice-I need both levels balanced in the top third of their ranges. However there are some on here on Combo who have ft4 levels below range and they are well as long as their Ft3 is near the top of its range.
I saw in your profile that you take 100 mcg of T4 and 20 mcg of T3. That is more or less the same ratio as in NDT...and you manage to get both your FTs in the upper part of range on that dose? I am asking because on NDT, my FT4 levels drop to the bottom of range when my FT3 is 75% through range. I need my FT4 levels higher. However, when I raise NDT, my FT3 ends up above range and I get hyper symptoms. I have been wondering lately if synthetic hormones are absorbed differently than the hormones in NDT, and if that can somehow affect hormone levels...?
I am about to get bloods done after 8 weeks at that dose so will see how high ft4 is. Might need another levo increase. Some folk need to add levo to ndt to get the frees balanced.
The problem with this work is that one can ask the question: OK, T4 and T3 were stimulants, but with the case of T4, was it converted in the cells to T3 before acting? I don't think this experiment proves a direct action of T4. And interestingly, later work has shown that T2 DOES potentiate mitochondrial action.
Precisely what I was thinking.
When I first came across people who both have no thyroid and dose on T3 only, I was surprised that at least some of them do very well. If T4 itself were so important, indeed vital, I'd have expected such people to suffer consequences of having no T4 available.
is the T4:T3 ratio in NDT wrong?
Is it ok to have low T4 if you're on T3 only?
Armour to t4/t3 combo 
T4 to T3 conversion troubles 
changing from t4 to t4/t3
