Hi, Erik:
If it were me, I would be strongly tempted to hold off on RAI and get regular bloodwork done. I haven’t heard of “extremely high” thyroid levels that don’t cause any symptoms, but your wife knows how she feels better than anyone else. If the heart rate is normal, it seems like it wouldn’t be in danger of damage. This is only my musing, I certainly don’t know for sure. Thyroid is nothing to ignore, but your wife seems like a special case. I hope you get some answers to your dilemna.
Best of luck,
Elaine