Bone Density Measurement Basics: Key Points
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- DXA (dual X-ray absorptiometry) is the preferred method of bone mass measurement.
- Peripheral bone mineral testing (testing of wrist, finger, or heel) is less reliable and should be confirmed by DXA scan.
- Medicare and most private insurers will cover DXA scanning under specific circumstances.
- Bone density test results include: T-score equals the standard deviation (SD) from the mean of a young-normal population; Z-score equals the standard deviation from the mean of an age-matched population; absolute bone mineral density (BMD) as grams of mineral per centimeter squared.
- The T-score is used to define osteoporosis/osteopenia and in treatment decisions.
- The Z-score may be useful in determining who should be evaluated for secondary causes of osteoporosis.