What is a DEXA Scan? Dual-Energy X-ray Absorptiometry

What is a DEXA Scan? Dual-Energy X-ray Absorptiometry
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DEXA (central machine)

What is a DEXA scan?

A DEXA (Dual-Energy X-ray Absorptiometry) scan is a form of x-ray that measures bone mineral density (BMD). It is the preferred method for measuring BMD (instead of a regular x-ray) because it is more accurate, requires less radiation, and is less expensive.

What is a DEXA scan used for?

A DEXA scan is used to diagnose osteoporosis, a disease in which the bones become very fragile and are vulnerable to breaking easily. It is also used to assess ones risk of breaking a bone and to assess the progress of osteoporosis treatment.

LVA (Lateral Vertebral Assessment) is an additional procedure (low-dose x-ray) performed on the DEXA machine to examine the spine for vertebral fractures.

How is a DEXA scan performed?

There are two types of DEXA machines:


The central DEXA device is a large machine that measures BMD in the spine and hip. To have this test, the person will need to go to a hospital or medical office.

The person will be asked to lie on a padded table. When viewing the spine, the legs will be supported on a padded “box” (to flatten the lower spine and pelvis) and when viewing the hip, the foot will be placed in a brace (to rotate the hip inward). An imaging device located above the person will slowly pass over the area being examined, generating the images on a computer monitor. While the image is being taken, the person will be asked to lie very still and hold their breath for a few seconds.

The whole procedure can take about 10-30 minutes. A LVA test can add on a few more minutes.


The peripheral DEXA device is a much smaller piece of equipment (a portable box-like structure) that can be used in mobile health vans and in drugstores. This device is used to measure BMD in the wrist, finger, or heel and usually takes just a few minutes to complete.

Who should have a DEXA scan?

People who are highly recommended to have a DEXA scan include post menopausal women, women who have had a complete hysterectomy, men or women who have suffered a fragility fracture after the age of 40, and those with certain medical conditions such as type I diabetes, liver disease, kidney disease, hyperthyroidism, hyperparathyroidism, and rheumatoid arthritis (RA).

Having a family history of osteoporosis or hip fracture, taking certain medications (including corticosteroids and some anti-seizure drugs), drinking excessive amounts of alcohol, and smoking also puts one at risk for osteoporosis.

A LVA test may be recommended for the elder who have lost more than 1 inch of height or who have unexplained back pain.

Health insurance/Medicare may or may not pay for the examination. The cost can vary and is normally under $300.

What is required before a DEXA scan?

• Normally, there are no restrictions on eating or drinking prior to the test.

• Calcium supplements should be discontinued 24-48 hours before the test.

Women who are pregnant should not have a DEXA scan done unless absolutely necessary (a woman who thinks she may be pregnant should inform her doctor). If a “contrast” x-ray or nuclear scan was recently done, one may have to wait 7-14 days before having a DEXA scan.

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