Thyroid UK
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T3 skewed blood test!

I've been privately taking T3 for some months along with my prescribed levothyroxine because they refused to up my dose of levo as I was "within range" even though levels had crept up and I had massive hypo symptoms. Then they requested a blood test so I stopped taking T3 for 5 days prior BUT levels were crazy! I'd read on here that T3 goes out of system very fast so thought I'd be OK. Obviously the depressed TSH doesn't bounce back up as fast. Can anyone advise me what to do prior to next blood test please? I'd prefer my GP not know I've tried self medicating, and have it on my medical record forever :( My serum TSH was 0.01 mu/L where normal reference range is given as 0.27 - 4.2 and my serum free T4 level was 8.3 pmol/L where reference is given as 12 to 22. They've asked me to go for another blood test in 2 months, so what can I do before then? I read recently someone saying that TSH level may never go back up?? Thanks for any help / advice x

6 Replies

That's right, your TSH may never rise again. And it doesn't rise very quickly, anyway. It's not instant. And, certainly your FT4 will not rise in five days. There really is no way that you can hide the fact that you're taking T3. Not that I know of. Why are you so afraid of telling your GP and having it on your notes? It's not illegal.


Thanks Greygoose, I'm doctor phobic already, avoid them wherever possible, and resorted to T3 after asking for more levo and instead being advised to take antidepressants ~ even though I categorically said I am not depressed, just chronically exhausted. Having read the same story over and over when I found this forum, I decided to try T3. It didn't seem to make much difference but now I've stopped I'm feeling more tired and brain foggy, even though they've upped my levo... I don't want them to wash their hands of me, or refuse to give me levo.


Yes, I understand, but... As Clutter said, it's best to come clean sooner, rather than later. And, after all, you are saving the NHS money by buying your own T3! :)



If you stop taking T3 your TSH and FT4 should recover in time for your next test in 2 months. You must be taking a high dose of T3 to have suppressed your FT4. If you continue taking T3 I recommend you have FT3 tested to ensure FT3 remains within range. You can order private thyroid tests via

On Levothyroxine only your GP would expect to see TSH within range or slightly below with FT4 in range. If you intend to continue taking T3 you need to come clean with your GP. You are entitled to self medicate if you want to but it will be taken amiss if you waste your GPs time by not telling him/her that your self medication is why your thyroid function test is off.

1 like

Thanks for the swift response and good advice Clutter x


My T4 went under range at 25mcg T3 (but not on 18.75) so you don't have to take much to make it fall (but I'm not taking any T4)


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