Interesting--husband had thyroid cancer 24 yrs ago (still feels the cancer was due to the radioactive iodine he administered to his lab rats for experiments ) and underwent removal of one half his thyroid--he took thyroid supplements for a year or 2, but was never able to regulate the dosage (kept becoming hyper thyroid) so he stopped the supplement. since his lab tests are within normal limits, it was assumed his remaining lobe of thyroid took over for the missing one---hmmmmmm.