What is DEXA (bone densitometry)?

Osteoporosis screening and diagnosis

Osteoporosis is a potentially debilitating disease that results from the loss of bone tissue over time. Some bone loss is normal with age. Bone loss that has not yet reached the level of diagnosable disease is called osteopenia. One of the most challenging aspects of osteoporosis is that osteopenia often causes no symptoms and is not detected until it has reached the level of osteoporosis, a disease that leaves patients at much higher risk of damaging fractures, especially of the spine or hip.

Although both men and women can develop osteoporosis, women are at much higher risk. The good news, however, is that osteoporosis can be treated much more effectively if detected early. DEXA (which stands for dual-energy X-ray absorptiometry and is also called bone densitometry or, more simply, bone density testing) is a fast, painless, low-dose X-ray exam that can find signs of beyond-normal bone loss at early stages. It can help identify patients who may be at risk of developing osteoporosis and may benefit from treatment.

Since women in the years that follow menopause are at higher risk of bone loss that could lead to osteoporosis, the American College of Obstetricians and Gynecologists (ACOG) and other organizations recommend DEXA screenings for:

  • All women at age 65
  • Women who are entering menopause as a test to help evaluate the potential benefits of hormone-replacement therapy
  • Women with a smoking history
  • Women with a maternal history of hip fracture
  • Tall (5 feet 7 inches or more) or thin (weight under 125 pounds) women
  • Men or women who may be at higher risk for bone loss, such as those taking medications that have bone loss as a potential side effect, patients with thyroid or parathyroid disorders associated with bone loss, or patients with illnesses or conditions associated with bone loss
  • Men or women with a family history of osteoporosis
  • Patients with kidney disease, liver disease, or Type 1 diabetes
  • Patients with urine test results that show excessive collagen, a possible sign of high bone turnover
  • Patients who have suffered a fracture after only a mild trauma or whose X-rays show signs of spinal fracture or other evidence of osteoporosis
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OsteLateral vertebral assessment (LVA):

A related exam for signs of osteoporosisoporosis screening and diagnosis

For older patients, doctors may also recommend another low-dose X-ray exam related to DEXA called lateral vertebral assessment (LVA). The purpose of LVA is to screen for vertebral fractures. Like bone densitometry, the exam is performed on a DEXA machine. The exam is especially recommended for older patients who have borderline readings on a DEXA bone density screening, as well as those with height loss of more than one inch or unexplained back pain.

Your test should take from 10–30 minutes depending on what parts of your body are being scanned.

  • If you need to undress and put on a gown, you will first be taken to a private area to change.
  • During the exam, you will lie down on a padded table, with an X-ray tube below you and a special camera above that can “see” the X-rays.
  • The technologist will help you get into a position that makes the areas of the body to be imaged—usually the spine and hip—most visible.
  • To help with proper positioning, the table may include:
    • A box to support your legs and flatten your spine against the table
    • A brace to support your foot and rotate your hip inward
  • To ensure quality images, the technologist will ask you to lie as still as possible during your scan.

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