Bone Density Scan
Then you should get one now.
I imagine you've had a calcium level done. Usually it's done as part of a CMP (comprehensive metabolic profile). It doesn't tell you much about whether or not you're getting enough calcium, though, because if you're not, you will just leach it out of your bones to keep the level in your blood good.
Please note: I AM NOT A DOCTOR. If you want medical advice, talk to your doctor. Whatever I post, there is probably some surgeon or other health care provider somewhere that disagrees with me. If you want to know what your surgeon thinks, then ask him or her. Check out my blog.