11BMDInterpretationandNormalRanges-National.PDFVIP

11 BMD: Interpretation and Normal Ranges 11 Introduction Bone mineral density measurements are frequently used in clinical practice to assess fracture risk. The utility of these measurements depends on making the correct interpretation. This involves comparison to an appropriate reference range and making allowance for independent factors affecting fracture risk. Interpretation of Results Correct interpretation of a BMD measurement will be influenced by the reason for the measurement. In this section we will consider the interpretation of measurements made for the following purposes:  To diagnose osteoporosis  To evaluate fracture risk  To determine whether treatment is required Section 13 addresses the interpretation of changes in BMD assessed from serial measurements. In order to make a meaningful interpretation, the BMD result must be expressed unambiguously, and compared to a relevant reference range. We need to understand the relationship between BMD and fracture risk, and take account of additional factors that affect the risk of fracture independently of BMD itself. Expression of BMD results BMD results may be expressed in various ways, which may each be useful in different circumstances: 2  Absolute BMD (in the case of DXA in g/cm ) Absolute BMD values are frequently reported but are only meaningful in the context of what is normal for a measurement made at the same site in an individual with the same characteristics.  As a standard deviation (SD) score Results expressed as an SD score compare the individual’s result to a reference range, which should be for individuals of the same gender and ethnic background. Comparison may be to an age-matched population, in