T4 before a blood test

[kirsty1946]

Asking the question again as seems to be conflicting info. I take T4 late at night so always thought I should skip this for early morning bloods......right or wrong?? Thanks

[greygoose]

You should leave 24 hours between your last dose and the test. Any less with give a false high, and any more will give a false low. So, the day before the test, could you not take your levo in the morning, instead of at night, just for once? It won't matter in the greater scheme of things.

[kirsty1946 in reply to greygoose]

Thank you. I really did think it was right so phew. Just I skipped for bloods then gp tested again without me knowing along with other bloods 2 wks later. FT4 12.5 then 19.5. I did tell him why the diff...luckily he still advised to raise T4 slightly! Xx

[kirsty1946 in reply to greygoose]

And yeah i will take in morning so as not to leave such a gap. I also take T3 twice but have skipped it on morning of bloods x

[greygoose in reply to kirsty1946]

Yes, with T3, it should be a 12 hour gap.

[kirsty1946 in reply to greygoose]

Great thanks. X

[greygoose in reply to kirsty1946]

You're welcome.

[kirsty1946]

Would u believe a thyroid forum on facebook??!! I skip the night before a test but then could be too long as per previous reply so day before test i will take in morning x

[kirsty1946]

So I am assuming the 12.5 was nearer the true value and def not 19.5....least gp isnt daft and told me to increase anyway x

[kirsty1946]

Mibbes slightly off at 12.5 tho do you think if im skipping night before? Then by morning of bloods ive not had any for 36hrs?? Its what ive done since taking them at night 😔

[kirsty1946]

Great thank u so much will carry on as I have been then. That was a glitch as didnt know they were running the thyroid tests again...not sure why they did tbh?! 12.5 would seem more likely as I got it tested first time as I felt totally rubbish! X