Bobbi – That is what has happened to me as far as there still being thyroid tissue after RAI and causing me (along with the replacement) to go hyper. I have been told to stay off of the replacement and see what happens. I get my blood checked in January. I didn’t take any replacement for months after RAI because my levels never got low enough. My endo is concerned that I will go hyper again even off the meds and then wants me to consider RAI again. I am not interested in that though. I’m with you – I wish there was much more studying going on about immune systems, stressors and thier effect on immune systems.