Whenever I go for a checkup, I take my Euthyrox in the morning and the blood sample is drawn 1-2 hours after intake.
I've recently read that FT4 is at its peak 2hours after levothyroxine intake. This makes me think the result is actually the FT4 at its highest.
Is there a way to know what is the FT4 baseline level other than taking a blood test without ingesting Euthyrox before ?
Is there a sort of formula or range to calculate the baseline level?
Could there be big variations between peak and baseline?
Please note I had a Total Thyroidectomy, so Euthyrox is my only source for FT4.