m not sure where your quote comes from, but I did check out the study from
NEJM that it references. The
NEJM study in no way says that up to a quarter of people with Hashi's spontaneously return to normal. In fact, in the study, only 9% of people with Hashi's even had positive thyroid stimulating blocking antibodies, and of that 9%, less than half saw their blocking antibodies go into remission.
I would have to wonder where all those people whose TRab went into remission are.