A bone density exam, which measures bones at several places in your body, can determine whether you are at risk of developing osteoporosis or have already developed it. The exam also can monitor the effects of taking bone-building drugs, such as hormone replacement therapy (HRT), alendronate and calcitonin.

During the bone density exam, you will lie on a table while a scanning device - either dual-energy x-ray absorptiometry (DEXA scan) or dual-photon absorptiometry - passes over bones in your hip, spine and forearm. The exam is painless and takes less than 20 minutes to perform.

Other devices that may be employed include a CT scan or single-photon absorptiometry.