Hi. After reading posts, I've noticed that it's advisable to fast and to not take medication until after the test. Surely this will only provide the doctor with an incorrect result because meds are supposed be taken at the same time every day. That means TSH levels are going to fluctuate and dosing would be incorrect. My Gp and the nurse both advise that I take my meds as usual and the amount of thyroxin I'm taking at the time of the test will be taken into consideration. As a nurse myself, who often discusses testing and results with my patients, I also wouldn't support this pre testing advice. I would never ask a diabetic patient to withdraw insulin before a blood glucose check, same principle applies with thyroxin.