Thyroid UK

Free T4

I have been adding T3 to T4 for 9 months. (now taking 25mcg T3 - 25mcg T4)

When on T4 alone,:-

in Oct 2009 my free T3 was 5.2 pmol/L (3.0-6.5) andT4 was 22.2 pmol/L. (10.0-23.0) SR

Adequate Thyroxine Replacement. TSH Lo 0.03 mu/L (0.35-5.50)

I am now on T3/T4 and today my Free T3 is 4.8 pmol/L (3.0-6.5) and free T4 is Lo 9.6 pmol/L (10.0-23.0) SR

(borderline free T4 probably Euthyroid)

TSH Lo 0.16 mu/L (0.35-5.50) SR

Is it because I take less T4 and the T3 goes directly into cells that the free T4 is lower?


7 Replies

Yes more than likely.

Thing is, when you were on T4 only, the free t3 was ok, you look like you could convert ok.

Why did you decide to take t3? Did it make you feel any better?

If not, is it because the cells are not using it? You need good ferritin, B12, D3, Zinc and Copper levels to be able to use T3. How are the adrenals too?



For the first four months on T4 I was improving (TSH when diagnosed 100), but then I was never well with stacks of side effects that are treated as separate conditions, although blood tests were always 'in range' so the theory is you should be back to full health.

The endo finally gave me a trial of T3 with the T4 and from the second day I haven't looked back.. Nearly all side effects went although I still have a couple of things. and I have the odd 'off day'. The addition of T3 made me feel that my good health had returned.

My B12 is 2,000 (due to having pernicious anaemia and have B12 injections) My Iron is 100 and vit D is good and all other minerals etc. are good.

I tried to take meds for adrenals but had to discontinue as I had a sensitivity (probably caused by something in the T4.).

I would like to take T3 only.


can I ask why you would like to take t3 only? it is great that you have improved so much by adding the t3 but your Free T4 level needs to be at the top of the range really which you only achieve if you take more t4. You are taking a very low dose of t4, 25mcgs is hardly anything.


When I complained to my GP that I thought T4 was causing all my problems, he said the only way I could prove that was if I stopped taking it. I knew I could not do that without an alternative.

When I first added T3 to T4 I had a wonderful six weeks then the severe palps, etc, began again so I stopped the T4 for six weeks and everything resolved. I added the T4 again. I was given Eltroxin and palps faded away again.

When diagnosed the T4 was 75mcg and when T3 was added it was reduced to 25mcg.

I have read Dr Lowe's letters of July 12 2010 and also dated January 30, 2002 (I quote bits of this one )which is near the bottom of the page.:

"The short time that T3 is in the circulating blood isn't the limit of its beneficial effects on the body. When T3 binds to T3 receptiors on genes, the binding regulates ......................................inititated by the binding of T3 to T3-receptors occur in waves, and these waves far outlast the T3 that started them at the chromosomes. ........As a result, a singled dose of T3 will be long gone....before he or she experiences most of the benefitsof that dose - a molecular and metabolic yield that may smoothy spread out over one to three days.

I am glad that you have at last found a solution which has enabled you to enjoy your Christmas.

PS I have also consulted with another professional but I only got my blood results yesterday and I see my GP next week.


I have a very similar regime to you but unfortunately my health hasn't really improved as a result of adding T3 I'm finding it difficult to increase my dose of T3 due to intolerance like symptoms. I suspect my adrenals are not strong enough- I'm having them tested using the saliva test. I was on 100mcgs Thyroxine for about 12yrs and then 6mths ago I had a blip. Titrating my T4 made little difference. My endo put me on 50mcgs T4 and 40mcgs t3. I have only managed to get to 15mcgs of t3 so far.




I am so sorry you have been ill for such a long time, and that we all have such a struggle trying to get better.

I would have been completely lost if I had not had access to the web and finding this support site.

As far I have read, the purpose of thyroid replacement is the elimination of all symptoms!!!

There is so much evidence that syntheticT4 keeps many people ill, considering that there are some products which might suit us better, but it is practically impossible to trial them. I had a saliva test but my Endo wasn't interested at all by the result. I also couldn't tolerate the supplements but I am sure that was due to T4. We could well be thyroxine resistant or it may be due to fillers/binders.

I am also sorry that you haven't had such benefit from T3 as I have, but , considering you have been hypo for 12 years, would your endo permit you to come off T4 for a short time to see if you benefit from T3 alone or allow you to trial one of the dessicated products like nature-throid which I think is hypoallergenic.

Suze has found relief in purified thyroxine.

PS 40 mcg of T3 is equal to about 200 mcg T4.




Thanks Shaws, I know its a big big dose - not sure why he decided to increase so much, I saw him for the consultation near to Christmas and I wonder if his mind was maybe not on the job - who knows! Getting T3 from him was like getting a piece of gold! I think it would be a battle to get him to prescribe natural thyroid replacement, but will have a go anyway when I next see him. Everything is worth a try.



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