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Thyroid UK
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What does my T3 reading mean?

Hello all :)

I have Hashimotos thyroiditis and I'm on levothyroxine.

I have had several TSH tests over the years and sometimes T4, but rarely T3 so I am not too sure what the readings means.

My last blood test in January shows that my Free T3 is 4.10 (range 2.63-5.7). I am guessing that it's similar to T4 that the higher it is the better I feel right?

Thanks in advance! X

7 Replies

Hidden The aim of a treated hypo patient generally is for TSH to be 1 or below and FT4 and FT3 to be in the upper part of their respective reference ranges if that is where you feel well.

It's generally said that FT4 should be in the upper...


Yours is just mid-range, which would be too low for a lot of people. But it's how you feel that's the most important.

Did you have your FT4 tested at the same time? It's useful to compare them, because that will tell you how well you are converting your levo. :)

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Thank you Greygoose, I think we both submitted more less at the same time!

Results in Jan were:

T4 was 14.00, which normally at this level means I don't feel well at all. (I can't find results from when I was well but from memory were slightly over 17)

Anti-thyroid microsomal ab 722.8

That's great to know that T3 is a little on the low side of ideal as I thought the reading looked ok

Thank you for your help :)


Thank you SeasideSusie. My GP finally convinced me to reduce my Levothyroxine from 100 to 75 as my TSH was very suppressed and I was feeling well. The result was that my T4 went from 17ish down to 14 and my antibodies went through the roof (from 250 to 720). I felt awful after this reduction and put myself back on 100 end of Jan but what confuses me now is that my T3 seemed OK when I was feeling unwell!

I am finally seeing my GP tomorrow to tell him and I want to understand in advance what's going on with my thyroid as from my experience TSH is their focus.


They have been poorly trained. In fact I don't think they even know that T3 (the active thyroid hormone) is needed in every single one of our receptor cells in order for us to function normally. The TSH is meaningless unless it's well out of range for diagnosis. Even then it sometime doesn't reach the perfect number. In the rest of the world the criteria for diagnosis is around 3+. In the UK, it is 10. Some people suffer dreadfully when TSH if 5, never mind it reaching 10.

Doctors, as far as I know have been told that the TSH and T4 are all that is required. With these two, they wrongly believe anywhere in range is fine and first they adjust the hormones up/down willy nilly to try to keep the TSH somewhere in the range. Mistakenly believe that a low or very low TSH will give us a heart attack which is ridiculous.

Several papers have been written about the 'tyranny of the tsh' meaning we are kept unwell.


Bumbo As you are Hashi's, are you gluten free to help reduce the antibodies? Supplementing with Selenium L-selenomethionine 200mcg daily and keeping TSH suppressed also help reduce antibodies.

Gluten/Thyroid connection - chriskresser.com/the-gluten...

Hashi's Information:




It's understandable that your FT4 reduced when your Levo dose was reduced and that you're feeling worse with that level, but you could be one of those people who need a FT3 very high in range to feel well. It's not the number but how you feel. Do you know what your FT3 result was before, when you were on 100mcg Levo?

Your antibodies could just have been having a flare up at the time and that is what increased them so much, it might not have been the reduction in Levo, but your TSH was suppressed before and you haven't said whether it came back into range with the reduction and that could, of course, have affected the antibodies.

Yes, TSH does seem to be the main focus for a lot of GPs, many of us here have that problem :(

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Yes, I went completely gluten free about 20 months ago and my antibodies did reduce from the 450/550 mark to 250, which is why this 720 really shocked me! Also started taking selenium recently. I decided to up my dose immediately after I saw the results as we were having ivf this month so need everything to be going as well as it can.

My T3 was never tested when I have been on 100, it's been a struggle to even get my T4 checked sometimes!

Unfortunately, the lab made a mistake when my T3, T4 and antibodies were checked and omitted the TSH test! It was tested a couple of days after I got the results and upped my dose back to 100 and it was suppressed at 0.05, however I had to have it done with urgency as the fertility clinic needed this urgently, and I had taken my levothyroxine that morning.


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