Question

Diagnostic Imaging

How does a bone density test work?

A Answers (2)

  • AMichael Roizen, MD, Internal Medicine, answered

    Bone density tests work by giving a measure of a bone’s mineral content. The dual-energy x-ray absorptiometry (DXA) scan is the most common bone density test. It passes a beam of x-rays through a large bone, usually the spine or hip. The x-rays blocked by dense bone are different from those blocked by soft tissue. Based on the amount blocked by dense bone compared to soft tissue, you can figure out how dense your bones are.

     

    Another common bone density test is the ultrasound. This method bounces sound waves over bone (typically, in your heel) to see if it bounces off. The only down side to this test is that you can’t use this method to assess the spine or hip, the most troubling spots for osteoporosis, or to monitor the effectiveness of osteoporosis treatments.
  • AHarris McIlwain, MD, Rheumatology, answered
    A bone-density test shows whether the bones are thinner than normal and cannot withstand the same amount of stress as they could in earlier years. So if a test shows low bone density, your risk for fractures and osteoporosis increases. Increasing your bone density lowers your risk for osteoporosis. This is a risk factor that can be treated and controlled.
Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.
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How can bone mineral density (BMD) be determined?