Dual Energy X-ray Absorptiometry
(Bone Mineral Density Testing; DEXA; DXA; Central DXA; Peripheral DXA)
This is a test that measures the density (or thickness) of your bones.
The DEXA scan is an x-ray scan that uses a small amount of radiation to take pictures of different bones. These pictures are used to measure the density of the bones at the spine, hip, wrist, and sometimes other sites, such as a finger or the heel bone. Measurements of the spine and hip are called central DXA. Those done on the arms or legs are called peripheral DXA. In some cases, your doctor may order a whole body scan.
Reasons for Test
This test will help your doctor assess the density of your bones and figure out if you have osteoporosis]]>, a bone-thinning disease. This information may be used to predict your risk of bone fractures.
What to Expect
Prior to Test
Description of Test
Total Body Measurement
You will lie on a table. A machine will pass over your body and take measurements of your bone density by sending a thin, invisible beam of low-dose x-rays through your bones. The amount of radiation is very small, less than 1/10 the dose of a standard ]]>chest x-ray]]>. A picture of your skeleton will be made based on how much the x-rays have changed after passing through your bones.
Spine or Hip Measurement
Your toes will be placed in a “pigeon-toed” position, and the same steps above are done.
You will sit in a chair beside the DEXA machine. Your arm will be placed in a holding device while the measurement is taken.
You will be able to leave after the test is done.
How Long Will It Take?
About 10 minutes
Will It Hurt?
The test results are usually available within a few days. Your test results will show two types of scores:
- T score—This number shows the amount of bone you have in comparison to a young adult of the same gender with peak bone mass. A score above -1 is considered normal. A score between -1 and -2.5 may mean you have osteopenia, the first stage of bone loss. A score below -2.5 means you may have osteoporosis.
- Z score—This number shows the amount of bone you have in comparison to other people of your age group, gender, and size.
These test results will help your doctor determine your risk for bone fractures.
The American Academy of Orthopaedic Surgeons
National Osteoporosis Foundation
Sartoris D, Dalinka MK, Alazraki N. Osteoporosis and bone mass measurement. Radiology. 2000;215(suppl):397-414.
Osteoporosis: bone density tests. Am Acad Orthop Surg Bull. 1999;47(3).
National Osteoporosis Foundation website. Available at: http://www.nof.org/. Accessed October 14, 2005.
Last reviewed November 2009 by ]]> Robert E. Leach, MD]]>
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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