I agree with Stella that you need to get a second opinion.....ALWAYS....with something this serious. I feel so aweful for you and your child and will keep you in prayer.
I do not have Graves but I did have RAI following my thyroidectomy for cancer and I was given prednisone to help with inflamation in my salivary glands and gums. Only, I wasn't very smart and I didn't take it after the 2nd day because it made me feel even worse than I already did. I should have taken it though, I ended up having issues that could have been prevented. Don't know if this helps but I thought I'd throw it out there.
Oh I am so sorry about this. I hope many respond here.
I was a short term Graves patient myself and underwent RAI - but I have no TED that happened to me.
All of the checking I did does state that RAI could cause TED symptoms to worsen - as for the actual percentile - I have no idea on how to answer.
She was just Dx'd with Graves 2 weeks ago and they are leaping into RAI right away?
Can't they start her on PTU treatment as a trial first to see if that helps with the Graves antibodies? That is usually the way they go about treating for Graves first - before ablating the gland.
She seems so young I would assume most doctors would want to consider PTU or methimozole first before permantely altering her gland. Did you get a second opinion? I think I would
RAI can be a miserable experience for an adult. I can't imagine it for a 3 yr old.