Bone Mineral Density (BMD) Test

What is a bone mineral density test?

A bone mineral density (BMD) test is a scan to evaluate your bone health. Bone formation and destruction continues throughout your life. As you age, the rate of bone destruction may be higher than the rate of formation. This can decrease bone density and make bone porous and weak, leading to a disorder called osteoporosis. Having weak bone can increase the risk of bone fracture even with a minor fall. BMD measures the strength of your bone.

The most common type of BMD test uses X-rays. These BMD tests are called dual-energy X-ray absorptiometry (DEXA) tests. DEXA scans use small, safe doses of radiation to look at your bones. You may also have a vertebral fracture assessment (VFA) along with a DEXA test. A VFA checks your spine for fractures.

What is the purpose of a BMD test?

Your healthcare provider may check your bone density to:

• Check your risk of fracturing a bone.
• Diagnose osteoporosis.
• Measure how well osteoporosis treatment is working.

Who needs a BMD test?

Experts recommend BMD tests for:

• Women or people assigned female at birth (AFAB) who are older than 65.
• Men or people assigned male at birth (AMAB) who are older than 70.
• People younger than 65 with a high risk of bone fractures.

Factors that can increase your risk of bone fractures include:

• Eating disorders that lead to low body weight.
• Kidney disease.
• Premature and early menopause.
• Rheumatoid arthritis.
• Sedentary lifestyle.
• Smoking.

No matter your age, sex or fracture risk, your healthcare provider may also recommend a bone density test if you have:

• Experienced a significant drop in hormone levels.
• Fractured a bone previously.
• Lost 1.5 inches (3.8 centimeters) or more in your height.
• Taken certain medications, such as steroids, long-term.

Who performs a BMD test?

A healthcare provider who specializes in taking and interpreting medical images (radiologist) performs a BMD test.

How does a BMD test work?

A BMD test sends low doses of radiation to your bones. These radiation doses calculate how much calcium and other minerals you have in each segment of bone. This calculation is called bone density.

How do I prepare for a BMD test?

Your healthcare provider will give you specific instructions to prepare for a BMD test.

Generally, you avoid taking any calcium supplements for 24 hours before the test. You also need to wear loose, comfortable clothing and avoid wearing items with metal zippers, buttons or belts. Remove all jewelry, eyeglasses, removable dental work or other objects that contain metal.

Tell your healthcare provider if you have a joint or dental implant. Typically, you can still have a BMD test if you have a permanent implant.

What can I expect during a BMD test?

BMD tests are outpatient tests, meaning you go home the same day. During the test:

1. You lie on a padded exam table.
2. A technologist positions an X-ray machine underneath you and another device called a detector above you.
3. The technologist goes into another room to activate the X-ray machine.
4. The detector passes slowly over your spine and hips to take images of your body. Your provider may ask you to move your legs or feet into different positions to take images of various areas. You may also need to hold your breath for a few seconds to prevent movement that could lead to a blurry image.

The test usually takes around 10 to 30 minutes. If you have a VFA along with a DEXA, your test may last a few minutes longer.

Who is not a candidate for a BMD test?

You may not be able to have a BMD test if you:

• Are pregnant or think you could be.
• Recently had a barium enema.
• Recently had a contrast injection for a CT scan (computed tomography scan) or other imaging test.

How long does it take to get the results of a BMD test?

Typically, it takes one to two weeks to get the results of your BMD test.

After the test, a radiologist interprets your imaging scans. The radiologist sends the results to your primary care or referring provider. Your primary care or referring provider reviews the results of the tests with you.

What do the results of a BMD test mean?

Your healthcare provider compares the results of your BMD test with the average bone density of a young, healthy adult. They calculate a number called a T score to assess your bone density. A T score of:

• Greater than -1 is healthy.
• Between -1 and -2.5 is slightly decreased bone density (osteopenia).
• Below -2.5 is osteoporosis.

What happens if I'm diagnosed with osteoporosis?

If your BMD test shows osteoporosis, your healthcare provider will offer treatment options. Many people can improve their overall bone health and manage osteoporosis by:

• Eating a healthy diet with enough calcium and vitamin D.
• Performing weight-bearing exercises such as walking, dancing or jogging.
• Taking osteoporosis medications to slow or reverse bone loss.

A note from Cleveland Clinic

A bone mineral density test is an assessment of your bone health. It measures the calcium and other minerals in your bones. How much calcium you have determines your risk of fracturing a bone or developing osteoporosis. Healthcare providers may also use BMD tests to diagnose osteoporosis. BMD tests are noninvasive, outpatient tests, meaning you don’t need injections for the test and you can go home the same day.