Osteoporosis Health Center
DEXA Scan (Dual X-ray Absorptiometry)
How is BMD measured?
Dual X-ray absorptiometry (DXA) is the preferred technique for measuring 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 2 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 2 beams, the bone density can be measured.
At present, DXA scanning focuses on 2 main areas -- the hip and spine. 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.
Osteopenia: Early Signs of Bone Loss
About 18 million Americans have osteopenia. Osteopenia refers to early signs of bone loss that can turn into osteoporosis. With osteopenia, bone mineral density is lower than normal. However, it is not yet low enough to be considered osteoporosis. Not everyone who has osteopenia develops osteoporosis with its painful, debilitating fractures. But osteopenia can turn into osteoporosis if it is not diagnosed early and promptly treated. Osteoporosis can result in easily fractured bones and other...
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WebMD Medical Reference from MedicineNet
Osteoporosis Guide
