Thyroid UK

Why are my FT4 and FT3 levels still low?

Good morning everyone.

Firstly, I must say that I was very surprised to have FT4 & FT3 tested last week. Normally I am told its not necessary and only receive TSH readings

Results: TSH 0.341 range (0.27 - 4.2).

Free T4 12.5 range (12.0 - 22.0

Free T3 3.4 range (3.1 - 6.8)

Medication: 80 mcgs Levo, 10 mcgs T3 x 2 daily

I have to say I am so much better than a year ago but I still suffer with fatigue, headaches, insomnia, vertigo and other less troublesome symptoms. I can go a couple of weeks feeling almost normal. But I always go back to feeling hypothyroid.

My thyroglobulin reading of six months ago was 313.3 (range <115).

I am gluten free.

My GP has commented that my ranges on the low side of normal. No follow up needed.

My question is why is my TSH level ok but my FT4 and FT3 still bottom of the range and what can I do to increase my levels. I'm not good at taking supplements as most of them make me feel nauseous.

I would like to comment on the amazing support here and for that I am so thankful

7 Replies

Your FT4 is bound to be low, because you are taking T3. Your FT3 is low because you aren't taking enough T3. The TSH is a very unreliable test. What time was the blood taken?

1 like

0830. No meds for 24 hrs beforehand and only water on rising.


Thank you for replying so quickly x


OK, so you can ignore the TSH - as I said, it's not a reliable test. Once you are on thyroid hormone replacement, your feed-back link no-longer works very well.

So, the problem is that you need an increase in T3.


Incremental increases....! Not sure if my GP will sanction it but I supplement privately as well anyway. Thank you greygoose x


I agree with greygoose. You definitely need a rise and it should be gradual until you have relief of all symptoms (not fit into a range to please the doctor). He of course will be wary as he doesn't want to be seen to ignore the 'guidelines'. You should aim to get your FT3 towards the upper part of the range not on the bottom.

I improved the more I reduced levo and increased T3.

P.S. I'm not medically qualified.


Thanks Shaws :)


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