DEXA Scan/Bone Density Test

Medically Reviewed By William C. Lloyd III, MD, FACS

What is a DEXA scan/bone density test?

A DEXA scan is a bone density test. Other names for it are bone densitometry, dual-energy X-ray absorptiometry, or DXA test. It uses enhanced X-ray technology to measure the amount of bone you have. It’s a common test for men and women older than 50 at risk of developing osteoporosis.

A DEXA scan is the gold standard for measuring bone density. However, doctors sometimes recommend another test—QCT (quantitative computed tomography). Doctors may use QCT in place of or in addition to a DEXA scan. Discuss all of your options with your doctor to understand which one is right for you. 

Types of DEXA scan/bone density tests

There are two types of DXA tests:

  • Central DEXA measures bone density in the hip, spine or arm. This test uses a large machine in a medical office or hospital radiology department to diagnose problems with bone density.

  • Peripheral DXA, or pDXA, measures bone density in the wrist, heel or finger. It uses a much smaller machine and is often available in pharmacies and mobile health units. A pDXA test is only a screening exam because it is less sensitive than a central test. It can tell your doctor if you need further bone density testing.

Why is a DEXA scan/bone density test performed?

A central DEXA scan shows whether you have normal bone density, low bone density, or true osteoporosis. It can determine if your bone density is improving, staying the same, or getting worse. This helps your doctor decide if you need to start treatment and if treatment is working.

Your doctor may recommend this test if you:

  • Are a woman age 65 or older or a man age 70 or older

  • Are a menopausal or postmenopausal woman younger than 65 with risk factors for osteoporosis

  • Are a man between 50 and 69 with risk factors for osteoporosis

  • Are older than 50 and break a bone

  • Have lost a half-inch or more of height in one year, or a total of 1.5 inches

  • Have unexplained spine pain

  • Take medication for osteoporosis

How is a DEXA scan/bone density test performed?

A DEXA scan is an outpatient test. It usually takes place in a hospital’s radiology department or an independent radiology clinic. A radiology technologist will perform your DEXA scan and a radiologist will interpret or read the results. Your test results are compared to standardized tables that are organized by age and gender. The radiologist will send the results to your doctor who will discuss them with you.

The procedure can take up to 30 minutes and generally includes these basic steps:

1. You may be asked to wear a patient gown or you may be able to wear your own loose-fitting clothing. You may also need to remove jewelry or other metal that could interfere with the images.

2. You will lie on a table for the exam. The technologist will position your body using supports and braces. The test itself is painless, but the positioning can be uncomfortable.

3. An imaging device will pass above the area of your body being tested.

4. You may need to hold your breath for short periods of time during the test.

5. You may need to wait briefly while the technologist verifies the imaging is complete. Usually, you can go home right after the exam.

Will I feel pain?

A DEXA scan is a painless imaging exam. However, the positioning of your body can be uncomfortable. Let the technologist know if you are more uncomfortable than expected.

What are the risks and potential complications of a DEXA scan/bone density test?

Risks of a DEXA scan are minimal. The test uses very low doses of radiation. The benefit of knowing your bone density far outweighs the exposure to low-dose radiation. However, women should inform their doctor and radiology technologist if there is a chance of pregnancy.

How do I prepare for a DEXA scan/bone density test?

You should stop taking calcium supplements for 24 hours before your test. Also, tell your doctor and technologist if you have had a barium exam or another imaging exam with a contrast agent in the last two weeks.

Questions to ask your doctor

Common questions include:

  • Why do I need a DEXA scan? Are there any other options for diagnosing or screening my condition?

  • How long will the procedure take? When will I be able to go home?

  • When and how should I contact you? Ask for numbers to call during and after regular hours.

  • When will I receive the results of my test?

  • How often will I need to repeat the test?

    What can I expect after a DEXA scan/bone density test?

    Knowing what to expect after a DEXA scan/bone density test can help you get back to your everyday activities without worry.

    How will I feel after DEXA scan/bone density test?

    DEXA scans are painless, noninvasive imaging procedures. If you experience any pain or discomfort after the procedure, alert a member of your care team.

    When can I go home?

    In most cases, you can go home immediately after all imaging is complete.

    When should I call my doctor?

    Keep your follow-up appointments after a DEXA scan and call your doctor if you have any questions or concerns between appointments. It’s helpful for both you and your doctor to write down your questions and bring the list to your next appointment.

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    Medical Reviewer: William C. Lloyd III, MD, FACS
    Last Review Date: 2021 Jan 10
    View All Bone Density Scan Articles
    THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
    1. ACR-SPR-SSR Practice Parameter for the Performance of Quantitative Computed Tomography (QCT) Bone Densitometry. American College of Radiology.
    2. Bone Densitometry. Radiological Society of North America.
    3. Bone Mass Measurement: What the Numbers Mean. NIH Osteoporosis and Related Bone Diseases National Resource Center.
    4. Bone Density Exam/Testing. National Osteoporosis Foundation.