Can someone please explain to me the difference between
I am going to a blood test tomorrow and they are gonna test my FT4, FT3 and TSH. Should they also check for F4 and F3 or is this enough???
FT4 and FT3 or free T4 and free T3 are the active thyroid hormones in the blood that are available to your body and what your body is "running" on. T4 or total T4 is bound and free hormone, only the free hormone which is about 0.05% of total is biologically active, Total T3 is also bound and free hormone.