Decrease (-) Restore Default Increase (+)
Bookmark and Share

Health Library

Multimedia Health Encyclopedia - Tests

Search Health Information   
 

Bone mineral density test

Definition

A bone mineral density (BMD) test measures how much calcium and other types of minerals are in an area of your bone.

This test helps your health care provider detect osteoporosis and predict your risk of bone fractures.

Alternative Names

BMD test; Bone density test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA

How the test is performed

Bone density testing can be done several different ways.

The most common and accurate way uses a dual-energy x-ray absorptiometry (DEXA) scan. It uses low-dose x-rays. (You receive more radiation with a chest x-ray.)

There are two different types of DEXA scans:

  • Central DEXA. You lay on a soft table, and the scanner passes over your lower spine and hip. Usually, you do not need to undress. This scan is the best test to predict your risk of fractures.
  • Peripheral DEXA (p-DEXA). These smaller machines measure the bone density in your wrist, fingers, leg, or heel. These machines are in doctor's offices, pharmacies, shopping centers, and at health fairs.

How to prepare for the test

If you are or could be pregnant, tell your health care provider before this test is done.

How the test will feel

The scan is painless. You will need to remain still during the test.

Why the test is performed

Bone mineral density (BMD) tests are used to:

  • Diagnose bone loss and osteoporosis
  • See how well osteoporosis medicine is working
  • Predict your risk of future bone fractures

You should have bone mineral testing or screening if you have an increased risk of osteoporosis. You are more likely to get osteoporosis if you are:

  • A woman over 65
  • A man over age 70

Women under age 65 and men ages 50 - 70 are at increased risk of osteoporosis if they have:

  • A broken bone caused by normal activities, such as a fall from standing height or lower (fragility fracture)
  • Chronic rheumatoid arthritis, chronic kidney disease, eating disorders
  • Early menopause (either from natural causes or surgery)
  • History of hormone treatment for prostate cancer or breast cancer
  • Significant loss of height due to compression fractures of the back
  • Smoking
  • Strong family history of osteoporosis
  • Taking corticosteroid medications (prednisone, methylprednisolone) every day for more than 3 months
  • Three or more drinks of alcohol per day on most days

Normal Values

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

  • T-score compares your bone density with that of healthy young women.
  • Z-score compares your bone density with that of other people of your age, gender, and race.

With either score, a negative number means you have thinner bones than the standard. The more negative the number, the higher your risk of a bone fracture.

A T-score is within the normal range if it is -1.0 or above.

What abnormal results mean

Bone mineral density testing does not diagnose fractures. Along with other risk factors you may have, it helps predict your risk of having a bone fracture in the future. Your doctor will help you understand the results.

  • T-score between -1 and -2.5 indicates the beginning of bone loss (osteopenia).
  • T-score below -2.5 indicates osteoporosis.

Treatment recommendation depends on your total fracture risk. This risk can be calculated using the FRAX score. Your health care provider can tell you more about this. You can also find information about FRAX online.

What the risks are

Bone mineral density uses a slight amount of radiation. Most doctors feel that the risk is very low compared with the benefits of finding osteoporosis before you break a bone.

Special considerations

Simple bone density scans using portable machines are often available as part at health fairs or screenings. These portable scanners check the bone density at your wrist or heel. Keep in mind that hip and spine scans are more reliable.

If you are diagnosed with osteopenia or osteoporosis:

  • Keep your bones strong by doing regular weight-bearing exercise such as brisk walking, tennis, or yard work.
  • Exercise such as tai chi improves balance and reduces risk of falls.
  • Check your home for fall hazards, such as loose rugs, to help reduce the risk of falls and fractures.

References

Lim LS, Hoeksema LJ, Sherin K; ACPM Prevention Practice Committee. Screening for osteoporosis in the adult U.S. population: ACPM position statement on preventive practice. Am J Prev Med. 2009;36:366-375.

National Osteoporosis Foundation. Clinician's Guide to Prevention and Treatment of Osteoporosis. Washington, DC: National Osteoporosis Foundation; 2008.

U.S. Preventive Services Task Force. Screening for osteoporosis: recommendation statement. Am Fam Physician. 2011 May 15;83(10):1197-200.


Review Date: 11/8/2012
Reviewed By: Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
 

Medical Care

Cancer
Pregnancy & Prenatal Classes
Weight Loss
Orthopedics
Heart Disease
Neurology
Women's Health
More Medical Care

Locations

Hospitals
Immediate Care
Health Centers
Emergency Room
Doctors Offices
Specialists
Affiliate Hospitals

Patients and Visitors

MyChart
Pay Your Bill
Request an Appointment
Get Healthy
Support Groups
Fitness Groups
Mobile Applications
Clinical Trials
Online Nursery
Classes and Events
Send an eCard
Patient Stories
Places to Stay

About Us

Quality Report 
Careers
Ways to Help
Community Outreach
Contact Us
(502) 629-1234

Connect with us

© 2014 Norton Healthcare
Serving Kentucky and Southern Indiana