I did a private at home thyroid blood test from Medichecks. I did it in the morning before tsking my Levo, the Ztsh Came back 3.94. GP would not accept it, so had s NHS blood test done at 4.25 in the afternoon after taking my Levo in the morning. My TSH was 5.04.
Could this be the difference in results as to when and how I did tests ?