My doc sprang a blood test on me last week (went about something else!) but I'd taken my levo about 2 hours before as I wasn't expecting it. I have never taken it before a test before and the result has come back TSH 0.09 (0.27 - 4.2). It was 0.13 a couple of months ago so I don't know if taking my tablets was signficant or not.
Many thanks,
Emma