Thyroid UK
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Should T3 and T4 results always be in top part of the range

Excuse me being a bit stupid here - bear with me as I am really trying to understand where the heck I am re recent blood tests results and it seems the more I read the less I understand and I have been reading a lot in the past few weeks!!

I know the TSH test results doesn't give much information. But re T3 and T4 - is it fair to say that for optimum thyroid health- are we always looking to have our Free T3 and Free T4 in top of the range?

So re my latest results below - should I be satisfied with my free T3 and T4 results or should I want that T3 and T4 result to be even higher? I feel I am still hypo but I know the results below look ok hence my confusion.

TSH 0.07 (0.3 to 4.5)

T3 free 3.64 (2.1 to 4.2)

T4 free 0.86 (0.7 to 1.8)


10 Replies

I think it varies from person to person. My recent tests showed mid-range Ft4 and top 1/4 of the range FT3, and I am feeling quite well.

This may not be the case for other people though - some need top of the range ore even above range - we are all so different.

Your FT4 looks quite low in the range... what dose are you on? xx


Hi Clarebear

Many thanks for helping on this. I am currently on 125mg of T4 and 40 mg of T3. I have been changing T3 dosage around to see if I can use the CT3M approach due to adrenal/dhea/testosterone problems.

So I take 20 mg of T3 at night before bed and then 20mg in the morning on waking. I think I need to bring that back to even earlier - maybe 5am ish. Then I take the 125mg of T4 late morning.

I know it varies for individuals but I am wondering if I need more T3 or more T4 or both?? Doctor is happy with my latest test results for Free T3 which has increased but my free T4 has gone down though still in range - doctor not too worried but I am wondering if I need to tweak something?. Just trying to repair adrenals fully and get hair regrowing and I am wondering what actual levels I should be aiming for in those test results as well as checking for physical improvements.


I am on T3 only and my FT3 is in the bottom part of the range. Now whether that is because I don't take my T3 before a test, I don't know. However I am well and feel normal.

I think if you are feeling unwell and your T4 and T3 are lower then there is a potential that increasing the levels will help you but it is not an across the board statement. Just like levo wont work (or will work) for everyone. Some do really well on levo, others do not.


Very interesting - I am not sure which I need more - T3 or T4. I haven't had any major health improvement or breakthrough for years.

I started on Armour and built up to 3.5 grains then switched to T3 and T4 which has been fine and no problem for me - but still not fully recovered - feel like that progress has been paused about 6 years ago (been on treating for 7 years)...

Interesting that you are only T3 only and are well and normal. Can I ask how much you take and what differences you noticed when you started on T3 only?


I noticed almost immediately the improvement on T3 once the T4 was removed. When on the combined treatment I did not do well at all. My good endo allowed the removal of T4 to see how I did and allowed an increase up to 40mcg of T3. Paul Robinson explained about the dividing dose so split my tablets into 4 lots of 10mcg and the effect was amazing.

Once the T4 left my system which is about 6-8 weeks, I have had a prolonged period of feeling well. Have messed around with the dose to get optimal and I think I am pretty much there. I am able to do all the things I want (and loads that I don't want to!). For example yesterday, I have my little girl, 5, off school for easter. We cleaned up the kitchen thoroughly, did laundry and put it on the line, we went into the garden for 5 hours and dug and weeded as we are totally renovating the garden so this is more than it sounds. I came back in, made dinner from scratch and dessert, cleaned up and carried on for the evening. Before the T3 only I would have been able to maybe do the laundry whilst caring for my little one.

My schedule is:

11pm (or as I go to bed) 20mcg T3 to support adrenals - I sleep beautifully and not disturbed.

7am (or when I wake up) 20mcg T3

11.30am 20mcg T3

I also take supplements of Vit D, iron, magnesium, selenium, cod liver oil, multi vits, B12 and B vits. I was low in iron and deficient on Vit D.

My TSH is generally around 0.5 or less, my FT3 is around 3.5 to 4.1 (3.5 being the lowest range on the hospital scale), my FT4 is unmeasurable according to the hospital. My Dr is fine with these results as he can see I am healthy and do not go to the Drs unless it is for my yearly blood test (never used to go at all before all this thyroid stuff).

Does any of this ramble help? :-)


Hi Poppy

Not a ramble at all - very helpful info! You sound like you are doing great and your energy levels are very high. Not just important for you but makes a huge difference to your family too.

You doctor sounds great too.

When you say your Free T4 is cant be measured. Is that because it is so low?

Like you I take 20 mg of T3 about 11pm at bed time - I agreed with you - it really helps me have a deep relaxing sleep. How do you split into 10mg doses - my T3 only comes in 20mg tablets!?



I got a pill cutter from the chemist. You will need to play around with it but I found putting the tablet around the middle to high end worked better for getting a more accurate cut. I then put all the bits left over on top of my bottle lid to take as the next dose so I didn't miss any of the lovely white miracle. Although I now take my tablets as 3 whole ones so no need to cut. My FT4 states that I am less than 3 so they do not measure any lower than that.

It was hellish before I got well, I have put up some blogs about it ages ago but I would not wish it on my worst enemy. One friend got up the courage to ask if I had cancer as she knew I had had biopsies and I was so ill. It took coming onto this site, seeing all the postings and information to make me take charge and get well. My GP is a really nice guy and he gives me a bit of faith in the medical profession (which given the history of myself and my husband is nothing sort of a miracle). Next lot of bloods I am going to ask him to test my female hormones and testosterone etc, make sure I am ok with all of those as I am at that wonderful time of a womans life - not!

It is great that you have got T3 and it does seem like more people are taking it now. Nothing would make me go back to T4 ever again. Not ever tried NDT but cant see why I would take it after getting my health back with T3.


Do you still have your thyroid gland?

Mine was removed, so i do better with t4 and t3


I would be tempted to try to increase the T4 to try and bring this up to midrange. Hopefully through conversion this will increase your fT3 too. If this doesn't work then maybe T3 only would be worth a try. Re CT3M, I think it is generally recommended to start on 10mcg 1.5 hours before waking/rising and the make adjustments in dosage/timing. However if trying more T4 would be best to do one or the other first so you don't change too many things at once. Xx


Thanks Clarebear.

I completely agree with you. I was thinking today about moving my T4 from 125mg to 150 and see what happens but keep T3 at same level to track any changes.

One problem I may have around splitting T3. I am on 40 mg a day and that is in the form of 2 tiny 20mg tablets. Do you split those tablets or is it possible to request t3 in 10 mg tablets - do you happen to know?

Many thanks



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