I am going through optimization of my Free T3 and Free T4 as my TSH has been on the high side but my Free T3 and Free T4 were always low. The doctor explained this as the brain is sending loud messages (high TSH) to the Thyroid to kick out more T3 and T4 but the thyroid gland is not able to pump out more T3 and T4. I started on 50mcg Euthyrox Levothyroxine and 5mcg Liothyronine and this lowered my TSH and bumped up my Free T3 and Free T4 but my doctor wanted my T3 and T4 to be slightly higher. So then I started on 88mcg Levothyroxine and 10 mcg Liothyronine. This resulted in extreme irritation, sweating and raised my 7-day average blood glucose more than 10 points - unacceptable. So now I am on 75 mcg Euthryox Levothyroxine 5 mcg Liothyronine (doctor said she may raise this to 10 in the future). It has only been a few days but I am experiencing hot flashes so I am not sure if this might be too high for me - will see what it does to the glucose. So I learned that to really find out how your thyroid is doing you have to measure all three - TSH, Free T3 and Free T4 - and you can't assume that high TSH automatically translates to high T3 and T4.
Wishing good health to all!