I usually do my labs around 7 am before work at a location close to my house, The last test was 3.93, but when I took my last lab 3 weeks ago it was at noon and was 2.31. Does time make a difference in the thyroid tests. My ultrasound shows enlarged thyroid. and antibodies but TSH in Normal range. Going back in 3 months and also having t4 and T3 tested.