Thyroid UK
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What level should my Free T3 be?

I am on 125mcg Levothyroxine and hyptT. In June my bloods were TSH 0.3 (0.4-5.5), Free T3 4.7 (3.5-6.5), Free T4 22.1 (11.5-22.7). I did feel better when my TSH was 0.05 last year - in fact I felt amazing and said to everyone "I"m back). But now I don't feel quite like that and am gaining weight again slowly - weight that came off when I was put up to 125mcg initially.

Although my T4 looks good here I wonder how good my T3 levels are. I think I'd like to try taking T3 with my T4 and see if it makes a difference.

Can any one advise me what a really good T3 level should be please?

Many thanks.


18 Replies

Your T3 level should be at the top of the range - have you considered that you may have a conversion issue i.e. your body is not converting the T4 you are taking into the T3 it needs. How are your iron levels, is your ferritin level (iron storage) above 70 as if this is not then this could hinder your body being able to convert they levo you are taking into T3.

Moggie x


Hi Moggie and CarolynB

My Ferritin was 5 (20-250) but after 16 weeks of taking Ferrous Sulphate I got it up to 40 (10-291). I then stopped the iron tabs and then about a year later the level had dropped back down to 27 (10-291). I don't understand why I don't store iron. I'm back on Ferrous Fumerate now and hope to see an improvement. The GP will prescribe these for 2 months. B12 is at 309 (210-910), and that's after taking B12 supplements for a year and a half. The GP doesn't think anything is wrong with that as it's within normal range. I've tried to explain that "I'm not normal, I have hypothyroidism." He did agree to give me 2 months supply of NHS B12 but these are apparently not as good as the supplements I've been taking. I don't know what is going on as I'm doing all the right things.

ANY advice is SO much appreciated.

Ali x


You probably need a sublingual B12 because it sounds like you are not absorbing well. Have you asked to be tested for pernicious anaemia? If you have PA you would need injections but sublinguals might work.

A B complex might also be a wise move. It contains B2 which helps your body store iron.

You might need to keep taking the iron, at a lower dose, once your ferritin is where it should be. Ferritin and B12 can make a huge difference :)


Hi, I have only ever been taking good quality sublingual B12 but it makes no difference. Dr won't entertain PA despite my telling him that my grandmother had it and that the best sublingual B12 has not made any difference.

I also just can't seem to get the ferritin levels up to the optimum levels recommended for hypoT sufferers.

I'm so fed up with the fight.

Thanks for your reply.



I think you need to see a different doctor. This one seems a useful as a chocolate teapot! If you have a family history this means that you are more at risk than most and it should at least be checked.

I hope you have more luck with a different doctor.


Yes I agree, but I might be jumping out of the fire into the frying pan. Not able to 'interview' a new GP first, how will I know if they have an even worse attitude/lack of knowledge about HypoT. I would love to more surgery but having seen 4 GPs now, this is the best of the bunch. I'm so cross that we have to ask for help and justify ourselves in wanting to be healthy and feel better. GGrrrr Thanks for your advice though - invaluable and interesting as always. x


Ps. I also take a Multi B supplement amongst other things.


A B12 of 309 after over a year of supplements (I assume methylB12 sublinguals?) is not normal, any doctor with half a brain should know that. My mother in law took them for about a month and got retested, at which time her levels were over 1500!

If the sublinguals don't do anything for you, I would stop them and retest your B12 in a month or two's time. Even better if you can get your doctor to refer you to St Thomas' for the active B12 and MMA tests (need to be clear of supplements for at least a month):

If you phone Denise Oblein she sends you some info for your GP and a registration form. I think you can post them the blood samples if you don't live near London, you'd need to ask her how to go about this. Your doctor's referral letter needs to include your name, DOB, and the name of test(s) requested.

Cost wise you're looking at £18 Active B12, £96 MMA, and if you wanted to go all in £40 homocysteine:

However, I don't think you can post the homocysteine blood sample, has to be done on site.

Alternatively, since you have a family history of PA, and an existing autoimmune condition, you could press your doctor to test anti intrinsic factor and anti parietal cells. You don't say if you have any symptoms of PA?



Hi Hamster.

I have some of the symptoms of PA but they cross over with HypoT, hair loss, sleep problems, poor concentration, dry skin, brittle nails - these things are not nearly as bad as they have been all of my life since I started on levo 2.5 years ago. I feel like this is DIY - there is too much to remember to take to the dr. Too many issues to deal with all at once, but I know they need sorting out. I wish the Dr would take the lead.

Thanks for your advice. I will try and get my head round it all and write it down and email him.

Many thanks



Oh, and the worse eyesight I've ever had. Going down hill noticeably - I don't know if that is a symptom of poor T3 conversion or poor ferritin or B12.


Have you ever had folate tested, or vit D?


Yes was right at the morbid end. I take a D3 supplement now.


Was folate low as well? You might find that if you get all these vits and minerals to optimum levels your T3 conversion might improve. But really first of all the doctor has to properly discount underlying conditions like PA or Coeliac disease, otherwise as you say you're just blindly going down the DIY route without knowing what the problem is. H x


Folate was 13.9 (5.4-24) so not great.


Actually, that's not bad. Mine was only 4 something a few months ago!


Not everyone gets on with t3 at the top of the range but it should be in the upper half of the range, in this case above 5. Your t3 is too low as Moggie says :)

I think you would probably benefit from increasing your dose back up to where you were. It seems that you convert ok (otherwise you may have felt worse at the higher dose rather than better). It is ok to have a TSH that is below range but 0.05 is pushing it a little with most doctors. Perhaps you can ask for an increase back to where you were but if your TSH goes below 0.05, and your doctor really won't accept this as ok, you could alternate between what you are currently on and the higher dose.

Moggie is right about the importance of iron. You may well find that just improving your iron/ferritin (if it is on the lower side) is enough to help you feel better. If not, ask for a small increase. If your GP is worried about having a TSH below range, I can find a paper that states that there is only an increased risk if your TSH goes below 0.03.

Carolyn x


Hi Carolyn

you seem so knowledgeable - and I am new on here ...

can I pick your brains pls ?

Assume ranges as above post - I just got my latest results :

T4 - 11.1

TSH - 1.62

T3 - 3.4

I have been on 50mg of levo for 5 years - never felt well and weight has gone up and up despite aggressive dieting - I now live on 1000 cal a day or less to maintain - feel fatigued and recently suffering with muscle weekness ( I have been put on a strong ant acid recently which may explain this ? - Omerprazol ) and and 52 and peri Menopausal ..also just been diagnosed with very high blood pressure - which I now know should be tested regularly with Hypothroisism ( and hasn't been ) as hypertension can be caused by Thyroid issues . I am convinced my doctor is in able to treat this effectively as never wants to join the dots ... HELP !!!! thanks


typo !! meant unable to treat ...


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