Although central bone density testing (also known as DXA) is the best way to predict hip fracture risk, peripheral bone density tests of the wrist or heel can be valuable screening tools.
The major issue in utilizing peripheral DXA as a screening tool is to differentiate those patients with low bone density from those with normal bone density.
As the peripheral DXA measurement gets higher, the chance of the central DXA measurement being low is less. When peripheral DXA measurement is higher than the average peak bone mass of a 30-year old, the chance of a central measurement being low is very small. Your doctor should decide if you need a central DXA if the peripheral measurement is less than 1 standard deviation below the average peak bone mass of a 30-year old (T-score < -1.0).
American Bone Health recommends that if you have a T-score from a peripheral screening test of < -1.0, you should talk with your doctor about getting a central DXA, especially if you are a postmenopausal women.
For more information about these guidelines, visit the International Society for Clinical Densitometry.
When would a central bone density test be helpful?
In general, peripheral DXA screening correlates with fracture risk. It is a good idea to take your screening results to your doctor and discuss whether you need a central bone density test.
If the T-score at your wrist or heel is normal… (T-score greater than -1.0)
- You may also have normal bone density in your hips and spine, but you cannot be sure.
- If you have other risk factors for fracture, talk with your doctor about getting a DXA.
If your T-score is low bone density… ( T-score between -1.0 and -2.5)
- You may not have lost any bone density, because you may not have reached a high peak bone mass by the time you were 30 years old.
- There could be medical conditions or medications that have caused some bone loss
If your T-score is osteoporosis… (T-score less than -2.5)
- Take your report to your doctor and ask for a central bone density test or DXA.