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Bone mineral density test

Contents of this page:


Bone density scan
Bone density scan

Alternative Names    Return to top

BMD test; Bone density test; Bone densitometry

Definition    Return to top

A bone mineral density (BMD) test can help your health care provider confirm a diagnosis of osteoporosis. The test can help in several ways:

How the Test is Performed    Return to top

Several different kinds of machines can do BMD testing. The most common methods use low-dose x-rays (about 1/10th the radiation dose of a chest x-ray).

While you are lying in on a cushioned table, a scanner passes over your body. Typically, the machine takes x-rays of your lower spine and hip. In most cases you won't need to undress.

There are portable machines that just measure the bone density in your wrist or heel, and some experts believe these are useful preliminary screening tools that can help identify people who may have osteoporosis. However, your bone density can differ from site to site within your body, so these machines may not give a true picture of your risk of a hip fracture.

How to Prepare for the Test    Return to top

Remove any jewelry before the BMD test. Inform your health care provider if you may be pregnant.

How the Test Will Feel    Return to top

The scan is painless, although you will need to remain still during the test.

Why the Test is Performed    Return to top

Your health care provider may request a BMD test to confirm a diagnosis of osteoporosis.

Normal Results    Return to top

The results of your test are usually reported as a "T score" and "Z score."

In either score, a negative number means you have thinner bones than the standard. The more negative the number, the thinner your bones. A T score is within the normal range if it is -1.0 or above.

Your doctor will help you understand the results.

What Abnormal Results Mean    Return to top

Risks    Return to top

BMD testing involves exposure to a low level of radiation. Most experts feel that the risk is very low compared with the benefits of identifying osteoporosis before you break a bone.

Considerations    Return to top

Regular BMD testing can be important in combating osteoporosis in certain people. The overall cost-benefit value of screening everyone, including those who are not at high risk, is still a matter of debate. Many insurance companies today will pay for bone density testing under certain circumstances.

Most experts agree postmenopausal women over age 65 years are at highest risk and should have bone density tests.

Woman under 65 may also be screened if they have additional risk factors, such as:

Simple bone density scans using portable machines may be available as part of health fairs or screenings. These portable scanners may check the density of your wrist or heel. However, keep in mind that hip and spine scans are more reliable.

References    Return to top

Gass M, Dawson-Hughes B. Preventing osteoporosis-related fractures: an overview. Am J Med. 2006;119:S3-S11.

National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis. 2008.

Update Date: 4/24/2008

Updated by: Peter Chen, MD, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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