Hi Needsinfo,
My second round of radiation hit me very hard. It was a high dose. If you look at the long list of possible side effects from being hypothyroid and radiated, I pretty much had them all with the exception of "menstrual irregularities!" Part of what you're feeling is the radiation, part is from being completely hypo. Everything hits you harder when you're hypo. I believe one of the reasons for the side effects being worse is this: When you have a total thyroidectomy, they usually leave in a small "tag" of thyroid tissue to act as a target for the radiation. But that tag isn't there by the time you have rad again, so when you are hypo, you are WAY hypo. It can be really hard to sort out which symptoms are from the radiation specifically, and which are from being hypo. But being hypo ampilifies the misery for sure.
All that being said, everybody's different! I know people who have been through the process and have suffered very little. (lucky!) There are really no ironclad rules for what does or doesn't happen with radiation.
Anyway, all of this was well over ten years ago and I'm alive and !**@!.
Best regards,
Richard Day Gore