Diagnosis

The most-reliable means of diagnosing osteoporosis is with a bone mineral density (BMD) test. The most-comprehensive test, using dual energy X-ray absorptiometry (DXA or DEXA), is a relatively quick, painless procedure that uses a very low dose of radiation (10 times less than you'd get on a round-trip, cross-continental flight) to measure the density of the hip and spine, where osteoporosis shows up first and is the most debilitating. Smaller machines using ultrasound to measure BMD in the extremities (typically the heel) are sometimes available at health fairs or in shopping malls, although experts debate their accuracy. One point is clear, however: If you have an ultrasound test that shows even marginal bone loss, talk to your doctor about having a DEXA scan as soon as possible.

Getting bone scans is especially important for women with major risk factors like menopause, eating disorders or prolonged amenorrhea. And experts believe many more premenopausal women could benefit from scanning, so those who don't know they've already lost bone can find out early.

You have osteoporosis if a scan reveals bone loss at any one site of at least 25 percent and osteopenia when results fall between 10-24 percent.