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Osteoporosis Health Center

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DEXA Scan (Dual X-ray Absorptiometry) to Measure Bone Health

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How is bone mineral density measured?

Dual X-ray absorptiometry (DXA) is the preferred technique for measuring bone mineral density (BMD). DXA has also been called dual energy X-ray absorptiometry, or DEXA. DXA is relatively easy to perform and the amount of radiation exposure is low. A DXA scanner is a machine that produces two X-ray beams, each with different energy levels. One beam is high energy while the other is low energy. The amount of X-rays that pass through the bone is measured for each beam. This will vary depending on the thickness of the bone. Based on the difference between the two beams, the bone density can be measured.

At present, DXA scanning focuses on two main areas -- the hip and spine. In certain situations -- if the hip or spine can't be measured, for instance -- it is measured in the forearm. Although osteoporosis involves the whole body, measurements of BMD at one site can be predictive of fractures at other sites. Scanning generally takes 10 to 20 minutes to complete and is painless and noninvasive.

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Osteoporosis and Diets

Weight loss and bone loss can sometimes go hand in hand. Doctors know that women with anorexia, who severely restrict calories for a long time, are at increased risk for osteoporosis. The eating disorder interferes with hormones needed to maintain bone, not to mention the foods people need to build bone. But what if you don’t have anorexia? What’s the relationship between osteoporosis and normal dieting? How do you know if you’re at risk for bone loss? What kind of dieting is safe for your...

Read the Osteoporosis and Diets article > >

WebMD Medical Reference

Reviewed by David T. Derrer, MD on December 29, 2013
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