I came across this article. Couple years old. Speculating on WHY there has been this sudden /surge/ in the occurance of cats having hyperthyroid. Years ago vThey suspect the surge of the use of plastic with that bad stuff in it? The one banned from baby bottles etc? It has been in mass use for other things like carpet padding, furniture padding, flooring, etc. And the chemicals shed off into the air and collect on dust as well. Which are all places cats spend most of their time.
I'm still heartbroken
So there's yer warning! Dust, vac, yearly vet, & maybe just keep a wary eye on yer cat.