let me chime in since i know somewhat about this subject being on thyroid meds for the last 15years. thyroid medication whether t3 or t4 builds up slowly in the blood stream..i repeat in the blood stream in other words urinalyses does not detect thyroid medication. i have taken both t3 and t4 it must be taken everyday and the levels build slowly in your bloodstream. therfore when i went on thyroid replacement they gave me a dose tested me 1 month after and adjusted accordingly tested another month and adjusted accordingly until after a year of a steady level then they kepp you at that level testing you every three months to make sure no adjustment is needed. thyroid hormone can not be detected via urinalysis. i give blood to check levels not piss in a cup.