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The test is typically performed to indicate the risk of osteoporosis or fracture. Bone density scanning, also called Dual-Energy X-Ray Absorptiometry (DEXA) or bone densitometry, uses X-Ray technology to measure bone loss or bone mineral density.

Two X-Ray beams - one with high energy, the other with low energy - are passed through bone. The amount of X-Rays that pass through the bone is measured for each beam. The result will depend on the thickness or density of the bone. A DEXA test is therefore an enhanced form of an X-Ray.

A DEXA test is a non-invasive test and it uses low levels of radiation. It is usually performed on the lower spine and hips and the results are extrapolated for the entire body. However, there are instances when the entire body is scanned.

Who needs DEXA ? : Post-menopausal women are prime candidates for a DEXA test. This is because falling oestrogen levels cause a gradual loss of calcium, as well as structural changes, causing their bones to thin, become fragile and more likely to fracture. This makes post-menopausal women prone to osteoporosis.

DEXA is also used to track the result of treatment for osteoporosis as well as other conditions that cause bone loss.

It also evaluates an individual's risk for fractures, which depends on age, body weight, history of fracture, family history of osteoporotic fractures and lifestyle factors such as cigarette smoking and excessive alcohol consumption.

A DEXA test is recommended if you :
  • are post-menopausal and not taking oestrogen
  • have a personal or maternal history of hip fracture or smoking
  • are a man with clinical conditions associated with bone loss
  • taking medication known to cause bone loss, including corticosteroids, anti-seizure medications, barbiturates or high-dose thyroid replacement drugs
  • have Type 1 Diabetes (insulin-dependent), liver disease, kidney disease or a family history of osteoporosis
  • have high bone turnover indicated by excessive collagen in the urine
  • suffer a thyroid condition such as hyperthyroidism or a parathyroid condition such as hyperparathyroidism
  • have suffered a fracture after only mild trauma
  • have had X-Ray evidence of vertebral fracture or other signs of osteoporosis.