Bone densitometry testing is notoriously inaccurate. It’s not a great test for osteoporosis or the predicting of fractures.
It is, however, a pretty good mechanism for monitoring whether you are getting better or worse. If a treatment plan for your skeleton has been initiated, bone densitometry at the beginning and end of it is probably a good idea as long as you go to the same machine.
Accuracy across different machines has been shown to be very non-reproducible.
For instance, if you have a bone densitometry test that says you do not have osteoporosis, but you have gotten an inch shorter than you use to be or you have had compression fractures in your spine, a shoulder fracture or a wrist fracture, then you have osteoporosis regardless of the official reading of the bone densitometry test. You need to be treated for bone loss. It is okay to monitor your progress with the densitometry test but it is a lousy diagnostic tool although it is heavily marketed otherwise.