DEXA (Dual–Energy X-ray Absorptiometry) is an x-ray procedure which is used to measure bone mineral density. A DEXA scan is a simple and non-invasive procedure. Measurements of the lower spine, hips and sometimes the wrist are taken. The procedure is painless and radiation exposure is minimal.




DEXA scans are recommended if you:
  • Are a post-menopausal woman not taking hormone replacement therapy.
  • Have a history of smoking.
  • Have experienced bone loss or bone trauma.
  • Have a family history of osteoporosis, fracture(s), hyperthyroidism and other related clinical conditions such as diabetes, liver or kidney disease.
  • Use certain medications known to contribute to bone loss as a side effect such as corticosteroids, prednisone, dilantin, some barbiturates and thyroid replacement medications.

Preparation

There is little or no preparation for a DEXA Scan. Eat as you normally do, however do not take any calcium supplements 24 hours prior to the exam. Dress comfortably and try to avoid garments with metal (zippers, belts, or buttons).

You may have to wait 10-14 days before undergoing a DEXA Scan if you have had another diagnostic study which required the use of a contrast agent such as barium enema, an upper/lower GI series esophagram; or have been injected with contrast material for a computed tomography (CT) scan or radioisotope scan for a bone or PET/CT scan.

As with all radiological procedures patients should inform the technologist if there is any chance of pregnancy.

How is a DEXA scan performed?

You will be asked to lie on the examination table for a short time while the arm of the machine passes over your body taking measurements. It is important that you stay as still as possible during the procedure to ensure a clear, useful image. A radiologist interprets the results of the DEXA Scan and provides a report to your primary care physician or gynecologist. DEXA report test results will be in the form of two scores a “T” score and a “Z” score:

T score — indicates the amount of bone you have when compared with 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 is classified as osteopenia, the first stage of bone loss. A score below -2.5 is defined as osteoporosis. It is used to estimate your risk of developing a fracture.

Z score — indicates the amount of bone you have when compared to other people in your age group and of the same size and gender. If it is unusually high or low, it may indicate a need for further medical tests.


If you would like additional information on these procedures we recommend you visit RadiologyInfo.org and the American Cancer Society.