@windyshores I've always wondered about percentage of change in bone density. I've never seen it explained anywhere. So I spent hours today trying to figure it out. The short answer is that the percentage of change calculated using BMD is not the same percentage as using if you used T scores.

On my DXA scan reports the percentage of change is reported based using BMD. I suspect that is what the usual figure is derived from in our discussions etc. If you do the calculation based on T-scores you get very different looking numbers just as you wondered about in your comment. If somehow you were given or calculated your own percentage of change using your T-score it could confuse everything.

Here's the formula for calculating the percentage of change which I got from bonup on inspire.com:
((New-Old)/Old)*100= percentage of change
I tried it and it works and matches the results I got from my DXA reports.
It works while using either BMD or the t-score but the numbers only make sense if you are talking about only one or the other. And since the BMD percentage of change is what is normally used a percentage of change from T-scores is just crazy making (the percentages look huge).
I think it makes sense that the numbers are not comparable but that's harder to think about and explain than just saying they are not comparable so I'll stop with that.