Koronin, I have two cats which have had the radioactive iodine treatment for their hyperthyroidism. The clinic administering the treatment should require a complete blood panel, a urinalysis and possible x-rays before they approve the treatment. Once cleared for the treatment the clinic administering the radioactive iodine should, as part of the price for the treatment, complete a full body ultrasound. If the ultrasound does not reveal any issues they should administer the iodine. Once your cat comes home you will also have some special instructions to follow for a week or so given your cat will still be shedding radioactive particles. After the treatment you should be required to return to your vet for additional lab work (typically a month and three months post treatment). Kidney function needs to be closely monitored as hyperthyroidism actually does the kidneys a favor and once corrected can reveal kidney issues post treatment. Be sure to follow their directions to the letter regarding post lab work. Best of luck and keep us posted.