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Bone Mineral Density

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Osteoporosis: Should I Have a Dual-Energy X-Ray Absorptiometry (DXA) Test?

Why It Is Done

A bone mineral density (BMD) test is suggested for:

  • All women who are age 65 or older, and younger women who are at increased risk for broken bones caused by osteoporosis.1
  • Men with risk factors for osteoporosis, such as being older than 70.
  • Men and women who have hyperparathyroidism.
  • Men and women who have been taking corticosteroids, such as prednisone, for a long time.
  • Follow-up of how well treatment for osteoporosis is working for men and women being treated for 2 years or longer.

How To Prepare

Avoid wearing clothes with metal buttons or buckles for the test. You also may want to remove any jewelry that might interfere with the scan, such as a bracelet if you are having the scan done on your wrist.

How It Is Done

A bone mineral density (BMD) scan is usually done in the special radiology department or clinic by a technologist. Peripheral dual-energy X-ray absorptiometry (P-DEXA) machines are portable units that can be used in a doctor's office.

You will need to lie on your back on a padded table. You can usually leave your clothes on. You may need to lie with your legs straight or with your lower legs resting on a platform built into the table.

The machine will scan your bones and measure the amount of radiation they absorb. The DEXA technique, which scans the hip and lower spine, takes about 20 minutes to perform. Other techniques may take 30 to 45 minutes.

Portable machines (P-DEXA) can measure bone density in the wrist or forearm.

Testing at least two different bones (preferably the hip and spine) each time is the most reliable way of measuring BMD. It is best to test the same bones and to use the same measurement technique and BMD equipment each time.

How It Feels

A bone mineral density test does not cause pain. If you have back pain, it may be uncomfortable to lie still on a table during the scan.


During a bone mineral density (BMD) scan, you are exposed to a very low dose of radiation. A BMD scan is not recommended for pregnant women because of the radiation exposure to the unborn baby.


A bone mineral density (BMD) test measures the density of minerals (such as calcium) in your bones using a special X-ray or computed tomography (CT) scan. Results are usually available in 2 to 3 days.

WebMD Medical Reference from Healthwise

Last Updated: August 30, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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