I always try to schedule my bloodwork in the mornings so that I can go before taking meds. My doctor did not tell me to go with out taking them so I didnt know. They couldnt get my levels right and finally I found info to do the blood work as Smilerdeb suggested "naked" and my tsh was showing as around .5 to .9 in the morning right after taking meds.. but it was actually the next week 2.6 without meds in the morning. That was a hugh difference to someone who gets hypo symptoms in the mid 2.'s.
Sally is right.
Always go 'naked ' for labs.
By that I mean...no thyroid meds lol.
If you take thyroid meds before labs...it gives a false reading on the FT3 and FT4.
You should wait until after the labs, to take your meds on the day of the test.
If you take your meds before the test (assuming both in the morning), your levels will be artificially higher becaue of the just taken meds.