Understanding DXA and Bone Density Results

If you suspect you have osteoporosis, then the easy way to check this, is to have a bone density test. In fact what you will have is a dual energy X-ray absorptiometry (DEXA or DXA bone densitometry). It’s painless, non-invasive, accurate and reliable, and involves a very low dose of radiation.

The scan is a high-precision type of X-ray that measures your bone mineral density and bone loss. If your bone density is lower than normal for your age, it indicates a risk for osteoporosis and bone fractures.

According to the International Osteoporosis Foundation, osteoporosis is estimated to affect 200 million women worldwide. Men also experience the condition, which weakens bones and makes them subject to fracture. Though more women than men have osteoporosis, men are more likely than women to die after breaking a hip.

Quick and accurate

  • The technique involves sending two X-ray beams at different peak energy frequencies to the target bones. One peak is absorbed by soft tissue and the other by bone. When the soft tissue absorption amount is subtracted from the total absorption, the remainder is your bone mineral density.
  • A DXA scan is used to determine your risk of osteoporosis and bone fracture. It may also be used to monitor whether your osteoporosis treatmentis working. Usually the scan will target your lower spine and hips.
  • Accuracy of the measuring process has significantly improved. Before DXA, the first sign of bone density loss might be when an older adult broke a bone. Standard X-ray diagnostics used before the development of the DXA technology were only able to detect bone loss that was greater than 40 percent. DEXA can measure within 2 percent to 4 percent precision.

Do you fit the ‘at risk’ group?

To be tested for the risk of osteoporosis, you need to meet at least one of the following criteria: if you are a woman over 65 or a man over 70; if you have broken a bone after the age of 50; if you display a medical risk factor history; if you are currently taking a steroid drug, such as prednisone; if you have primary hyperparathyroidism; if you have rheumatoid arthritis or chronic kidney disease; if you suffer eating disorders; if you have experienced early menopause (from natural causes or surgery); if you have a history of hormone treatment for prostate or breast cancer; if you display a significant loss in height; if you are a heavy smoker; if you tend to have three or more alcoholic drinks per day on most days.

How does it work?

  • DXA works by sending two low-dose X-rays which are absorbed differently by bones and soft tissues. The density profiles from these X-rays are used to calculate bone mineral density. The lower the density, the greater the risk of fracture.
  • DXA can determine bone mineral density for any bone but is most commonly used for hip and lumbar (lower) spine. The examination can also be used to perform vertebral fracture assessment. This screening is used to uncover bone problems of the skeleton, for example in people who have unexplained back pain or who have experienced a loss in height of more than an inch in a year. Vertebral fractures are often asymptomatic.
  • A bone mineral density assessment may be considered every two years, depending on age, gender, and other factors. Regular screening can diagnose osteoporosisand other bone problems early. That way they can be managed and even curbed with prescription medicines and lifestyle modifications.

The DXA is really the way you get to ‘see’ your bones! If you experience a sense of vulnerability with regard to your bones, or suffer a twinge or a twang – even when there’s no music – get the test. Get it done. Love your bones!

NOFSA (National Osteoporosis Foundation South Africa)

NOFSA is the only non-profit, voluntary health organisation dedicated to promoting lifelong bone health. We focus on reducing the widespread prevalence of osteoporosis while working to find a cure for the disease, and by supporting research and developing programmes of education and advocacy.

Find out more about our work at: www.osteoporosis.org.za