I’ve been checking into this topic a bit. I haven’t seen the published research yet, but a doctor who posts occasionally to alt.support.thyroid has responded to the issue. I once asked him for permission to take his messages from that board over to this one, and received it, graciously. Anyway this time I’ll paraphrase. There is published research that correlates EXCESS thyroid replacement (as demonstrated by a supressed TSH), with the speeding up of the expected loss of bone density with age. Similar studies found a connection to being HYPERthyroid. (See Ingbar/Braverman’s text, “Werner’s The Thyroid” in your local medical library.)
So, it hasn’t got anything to do with RAI. It may have something to do with synthetic thyroid replacement BUT the current studies show that it has more to do with just being hyperthyroid in the first place. Another reason to treat it, and avoid it! This also explains, a bit, why our doctors are so insistent upon keeping the lab values within the normal range, and perhaps even on the low side, with replacement hormones.
Sorry, but I just noticed something else that needs to be corrected. You do not lose your parathyroids when you have RAI. They continue to function. It is the surgical removal of the thyroid that can damage/remove the parathyroids, too, that can lead to having to take calcium replacement.