I'm hypothyroid (Hashimoto's) and currently experimenting with 15 mcg of Slow Release T3 (SR T3) together with 150 mcg T4. Note that my absorption is not the best, so 150 mcg T4 puts me around midrange of FT4.
I know on this forum it is recommended to wait 24 hours between the last dose of T4 and blood test i.e. take it one morning, then the next morning do the blood test on empty stomach and no hormones. With normal/pure T3 8-12 hours is recommended, which would mean taking it in the evening if the test is in the morning (2 hours after last meal and 1 hour before the next).
Slow Release T3 is different as the dose does not get absorbed at once, it keeps releasing small doses of T3 throughout the day. My theory is that I should wait 24 hours (just like with T4) between the last dose and blood test. This is to make sure the slow continuous releases have stopped as much as possible. If I test after 8-12 hours, FT3 is likely to be elevated as more T3 is coming in still.
My question to those with experience with Slow Release T3, what is the most correct thing to do here?