What is a bone density scan?

A bone density scan checks the density (thickness) of your bones. If your bone density is low, you have a higher risk of a bone fracture.

This scan is also called a dual energy x-ray absorptiometry scan or DXA scan. It is sometimes called a bone mineral density scan or BMD scan.

Who has a bone density scan?

Your GP or hospital doctor may arrange for you to have a bone density scan if:

  • a fracture risk assessment shows your risk of fracture is intermediate (between low risk and high risk)
  • you are under the age of 40 and have a significant risk of fracture – for example, you have had more than one fragility fracture, or have recently taken high doses of steroids
  • you have had an early menopause and you have not had hormone replacement therapy (HRT)
  • you are a woman with early invasive breast cancer and you:
    • are going to start treatment with an aromatase inhibitor
    • have had an early menopause due to your treatment
    • are going to have treatment to stop your ovaries working
  • you are a man with prostate cancer and you are going to start treatment with hormonal therapies that reduce testosterone levels – if you are on long-term hormonal therapy, you should have a DXA scan every year
  • you are taking steroids.

 

How the scan is done

During the scan, you lie on your back on a couch while a scanner moves above your body. The amount of radiation from a bone density scan is much less than from a normal x-ray.

The scan only takes a few minutes and is painless. It is important there are no metal fastenings such as zips in the area being scanned. You may be asked to put on a hospital gown for the scan.

Bone density scan results

The results of the scan will show whether you have:

  • normal bone density
  • low bone density (osteopenia)
  • osteoporosis

Your scan results are reported as a number called a T-score. Your T-score is your bone density compared with the bone density of an average healthy young adult of your gender. Your T-score is the number of units that your bone density is above or below the average.

What your T-score means

T-score


-1 and above

Your bone density is normal.

Between -1 and -2.5

Your bone density is below normal. Doctors call this osteopenia.

-2.5 and below

This score suggests you have osteoporosis. Your bone density is low and your bones are at higher risk of fracture.


After a bone density scan

If the scan shows you have low bone density your GP may advise you to:

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