Log in
Thyroid UK
93,525 members107,577 posts

When and how to take T3 before blood test

I'm due to have a private blood test this Thursday and would be grateful for advice as to when and how I should take my T3. Last year I took both my Levo (75mcg) and T3 (10mcg) 24 hours before the test. I have since learned that T3 should be taken 12 hours beforehand. That being the case, should I take the full 10mcg at 9pm the night before or split the dose and take 5mcg with the Levo on Wednesday morning and 5mcg at night? I'm just a bit concerned that the full dose will give me insomnia.....it may not, but so many things do. Thanks.

4 Replies

DoDoc I take a levo/T3 combo and take my T3 all in one dose early mornng. When I have a blood test I follow the advice about timing so I split my T3 the day before and take half in the early morning and half 12 hours before I know I'm doing the test the next day. I do it every time so results can be compared accurately.


Thanks SeasideSusie. I'll do that.



I just take my Levothyroxine and T3 as normal. As it's roughly 24 hours between last dose and blood draw I simply extrapolate FT3 result by +20% to estimate normal circulating FT3.


Thanks Clutter. Yes, i suppose I could do that


You may also like...