Stopping medication before a blood test...

[Tony63]

My partner has a blood test tomorrow (TSH,FT3,FT4) at 11:50am. She took Erfa at 6pm this evening. Is it essential to stop your medication 24 hours before a blood test? I imagine this question has been asked many times but I can't seem to find it.

[galathea]

She should be fine, Thyroid hormones peak in the blood a few hours after they have been taken, but she will have left it well over 12 hours.....

G

[Tony63 in reply to galathea]

Thank you for replying Galathea, that's a big help.

[Clarebear]

Personally I do prefer to leave it 24 hours, but think 12 hours is in line with STTM recommendations.