Blood Test Results - Hypothyroid - Free T3 & Free T4

Good Evening, I wondered whether any of you know please, what is considered low, high or what would be "about right" for Free T3 and Free T4 when taking Armour. I have just had some blood tests done and I am hoping like mad that my Armour needs to be increased as I am very underpowered!! I don't actually have the results yet otherwise I would post them. I just wondered if anyone you kind people knew what the levels should be to feel "well". I think the TSH should be about 1 ish. Thank you all kindly for your help.

10 Replies

Some people are well with a TSH of 1, but not everyone. And that's for people on T4 only. When taking any form of T3, your TSH is going to be lower.

FT4 will be low, too. But, neither the FT4, nor the TSH matter very much. The important one is the FT3.

The right level of FT3, is the one at which you feel well. Optimal is not a number on a lab sheet, it is the way you feel. Most people need the FT3 up quite near - or even slightly over - the top of the range to feel well. But we're all different.

There is no one number you are aiming for, you are aiming to feel well. Keep increasing until you do. :)

Good Evening Greygoose

Thank you very much indeed for your reply. That is very helpful indeed. An endocrinologist that I was seeing a few months back always said that you can't look at the numbers, it is how you feel. He was generally, at that time referring to the TSH. I have moved to a new area and have found a new (private) endo who WILL prescribe Armour if he can see by past history that Levo is not working. I was just so excited to be going onto Armour and really hoped that it would be the answer to my prayers and that I would start to feel better. In a nutshell I feel that I am either wrongly dosed (probably underdosed) or Armour does not suit me. I have been in touch with the endo who suggested I have some blood tests a couple of weeks ahead of the agreed time and I think he may increase my dose (hopefully), then see me after a repeat blood test in about 8 weeks. I feel that you have to trust yourself, only you know how you feel and if you don't feel right then you have to continue your journey. Thank you Greygoose for your help.

You're welcome. :)

:) Lovely to have such a supportive group - we learn so much on here!



Be sure to remember to take your Armour dose after your blood test or your FT3 will be too high.

Thank you Clutter. I am not sure how the figures will stack up because I take my Armour in the morning, all of it or I have even more difficulty getting through the day. Because I had felt so rough, I rang the endocrinologist and his secretary said get a blood test done. The next available appointment that I could make was that afternoon!! I had taken my meds at 7am. My appointment was at 5pm. I am hoping that my lack of Armour will still show as I feel so rubbish. If not, I will have to have another blood test done. I did wonder if my meds might interfere with mt blood test. Thank you very much for your kind help.


10 hours after your last dose the T3 will have stopped peaking in your blood so your blood test won't be skewed although TSH will be much lower at 5pm rather than 8-9.00 am.

Thank you Clutter. I am so very grateful for the advice you have given. It makes me feel better. Ummm, I suppose the TSH is a bit of a worry as it might show low at 5pm but in fact earlier in the day, it might have been high so would need medication to bring it down. Am I on the right track? I hope I haven't misunderstood. :) Thank you very much.


You are taking medication to raise your thyroid hormone and bring down TSH. Some doctors dose according to TSH so it is better if it doesn't show too low as they may reduce dose or refuse a dose increase. Members are advised to have early morning blood tests when TSH is highest and to fast beforehand because eating and drinking lowers TSH. Of course, it isn't always possible to do this but it is worth doing it if you can.

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