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Bone Density Scores

Bone density scores may sound like Greek.  They involve two alphabetic letters that Bone-density-scores | Articlecompare your fracture risk with that of other people.  While they are statistical measures, bone scans are not definitive. You can not be compare your scans to those of other people or even compare results from different bones to one another.  Many health professionals recommend collecting bone density scores on the spine and hip using a central dual energy x-ray absorptiometry (DXA) machine. DXA is considered to be the most accurate scanner and should be used by osteoporotic or osteopenic patients.

Other BMD equipment generates bone density scores that lack the diagnostic accuracy or reliability of DXA machines.  These include QUS, which employs ultrasound waves and other radiation emitting scanners such as pDXA QCT and pQCT.  Finally, there are BMD machines that best serve as first-cut screens for bone loss. One common ultrasound scanner measures the heel bone as an approximation of hip bone density. This scan is not reliable enough to track bone changes over time due to medication, exercise or natural bone healthy practices.

The University of Washington explains bone density scores as follows:  (http://courses.washington.edu/bonephys/opbmdtz.html)

“The T-score is the number of standard deviations below the average for a young adult at peak bone density. There are different T-scores depending on which group of young adults was used as the reference (for example, Caucasian women, Hispanic men). The Z-score is the number of standard deviations below an average person of the same age. There are also different Z-scores depending on the group used as a reference.  Furthermore, a person can have one T-score at the femoral neck, another at the total hip, and another at the spine”

The World Health Organization (WHO) established the standard that most professional use to assess bone density scores. These apply to Caucasian women:

•    Normal bone: T-score better than -1
•    Osteopenia: T-score between -1 and -2.5
•    Osteoporosis: T-score less than -2.5
•    Established (severe) osteoporosis
     includes the presence of a non-traumatic fracture.
Note:  WHO does not provide T or Z scoring for men or non-white ethnic groups.

Bone-Density-Scores | ArticleMayo Clinic.com reminds those trying to understand their bone density scores:

“that these scores apply mostly to white postmenopausal women, who tend to have lower bone density as compared with other racial groups and men. Interpretations may vary if you're a woman of color or a man.” 

Many doctors will perform bone density test results every two years, sometimes more often on women nearing or at menopause. Based on results, your doctor will suggest a testing schedule and offer suggestions to improve bone density.  For consistency, try to be tested on the same bone density scanner each time. This makes it easier for you and your doctor to monitor progress and accurately compare results to previous bone density scores.