Thyroid UK
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Not sure what my tests are showing???

Just had my most recent blood tests back on 50mcg of T4 and 20mcg of T3 per day. Endo wants me to reduce my T3 back down to 10mcg per day, as I increased it myself and he's concerned. I'm not worried and feel much better on 20mcg but not sure what my blood tests say on the higher dose. Obviously my TSH is lower but why has my T4 level dropped if I'm still taking the same amount as before and my T3 has only risen slightly from when I wasn't taking any. Anyone have any ideas???

Results as follows:

27/7/12 This was on T4 only at 100mcg

FT4 15.7 (10 -23)

FT3 4.5 (3.5-6.5)

TSH 0.13 (0.35-5.5)

18/9/12 This was on 50mcg of T4 and 10mcg of T3

FT4 12 (10-23)

TSH 0.14 (0.35-5.5)

No FT3 was done, which I thought was stupid seeing as I'm taking T3???

4/1/13 This was on T4 50mcg and T3 20mcg

FT4 11.3 (10-23)

FT3 5.1 (3.5-6.5)

TSH 0.07 (0.35-5.5)

10 Replies

Do bear in mind that time of day for the blood draws makes a difference. Have a look at an old blog:

And the article that blog refers to:

Shows that quite a bit f the difference could simply be time of day. But, of course, might not be.



Thanks but they've all been about the same time 9am ish :)


I think your fT4 is lower because your TSH is now supressed, so your own thyroid isn't being asked to produce much in the way of T4. Just a thought :D X


Oh okay, didn't realise that would be the case, thanks Clarebear that makes some sense. :) x


Dr Toft in his article says that if you add T3 to T4, the T4 should be reduced by 50mcg for 10mcg of T3. so theoretically that would mean maybe you should have reduced your T4 again when you upped the T3. I know when I took T3 alone the T4 was very low because I wasn't taking any., the GP didn't like that but Dr S and Dr P had no problem. T4 is inactive and T3 is active.


That would mean stopping my T4 all together, which I have also done and that made me worse again. I seem to definitely be better on some T4 or maybe I just need lots more T3 to compensate if I'm not taking any T4????

God this is so confusing lol


1mcg of T3 is approximately equivalent to 4mcg T4. By stopping the 50mcg of T4 you were then left on only 20mcg of T3, approximating to 80mcg T4.

80mcg of T4 (delivered by 20mcg T3 ) is a very low dose, most people's starting dose is 50mcg, titrated upwards at intervals of 6 weeks or so until an optimal dose is reached.

On such a low dose of approximately 80mcg T4 (from 20mcg T3 ) it is small wonder you felt worse.

You have been lucky enough to have the attention of an endocrinologist. Be very careful please or he or she might lose patience with your attempts to alter prescribed medication. You might antagonise him/her and yet they have been enlightened enough to let you have T3 whereupon you have promptly altered the dosage. Yes, you will be impatient to get results but I think that your endocrinologist is rather to be respected. Having such a person in charge of my care would certainly have spared me many years of suffering before the wonderful internet.



I totally understand what you are saying but previously I was only on 50mcg of T4 only so 80mcg surely would of kept me feeling better than I was before.

I do not want to antagonise my endo but if I'm still not feeling better what am I supposed to do, just put up with it???? They were going to discharge me completely and leave me on T4 only, until I increased my own dosage because they wouldn't. It was because of the effects of the self increased dose that they realised there might be an issue and offered me the T3!

I know my endo has no intention of increasing my T3 at all( I was already taking the lower dose for a couple of months), let alone gradually, otherwise I would have waited. It's not impatience, it's desperation!

So if my endo wants to continue to keep me on the 10mcg of T3 and I know I feel well on 20mcg of T3, what do you suggest that I do? If I have to i suppose I could buy my own T3 to top it up but then the endo may refuse to give me what I have now and discharge me anyway.

I do understand what you're saying but I have also been suffering for many years and it seems crazy that I know what makes me feel better but am being told I can't have it. It's torture.


Ok, Denise you have to do whatever you feel driven to do, but honestly, in your place I would stick to the endo's regulation of your T4/T3 and allow the timework element of treatment to work its effect. It is like firing ceramics, not enough to get the kiln up to temperature, the heat has to be given enough time to work.

I have T4/T3 treatment from Dr Toft. 10mcg T3. It took a year to repair major physical symptoms, but I do now feel very well though once I was an undiagnosed, ignored, balding, deaf, brain-fogged, slow-moving, burning muscled, hoarse-voiced exhausted wreck who looked like a gargoyle my face was so swollen. Lovely! But all gone now, but not overnight.

I agree with shaws point that if you have sucess with this endo then he would regard T3 favourably. He has been flexible-minded enough to recognise that T3 is necessary and that is truly one huge plus in his favour.

Perhaps you have to ask yourself where would you be if you do scupper his involvement with you which apparently has only been for six months or so, I see from the test dates, and that really is not enough time to assess improvement.

I guess this could come across as preachy, if so, I apologise.


nostoneunturned has given perfectly sound advice which you should take to heart. You cannot rush meds in order to feel better. It takes many months Most Endos will not contemplate adding T3, so you are very fortunate.

If you can have success with your Endo he wlill be more willing to prescribe some T3 to other patients.

It took me 3 years before I began to feel I was getting somewhere.


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