Could anyone tell me the blood tests I should be asking my doctor for? I have read a bit about it all but I am finding it really difficult to understand. I am currently taking 175mcg thyroxine per day but I am still ill. I have many underactive thyroid symptoms so it is not under control even though for 15 years everything was fine with the dosage, the last couple of years have been horrific. I have a doctors appointment first thing tomorrow so I would be really grateful for some advice.