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Definition
| Reasons for Test
| What to Expect
| Results
| Call Your Doctor
Definition
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
- Eat normally on the day of the test.
-
If you have had a barium study, or have been injected with contrast dye for a
CT scan
or
MRI
, wait at least seven days before having a DEXA scan.
- Wear loose, comfortable clothing. Do not wear clothing with metal zippers, belts, or buttons.
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.
Wrist Measurement
You will sit in a chair beside the DEXA machine. Your arm will be placed in a holding device while the measurement is taken.
After Test
You will be able to leave after the test is done.
How Long Will It Take?
About 10 minutes
Will It Hurt?
No
Results
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.
Call Your Doctor
Call your doctor if you have any questions about the test, your condition, or your test results.
Last reviewed November 2009 by Robert E. Leach, MD
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