Table 1.

Common mistakes in BMD testing.

Category	Mistake	Examples/comments
Indication	Not doing bone density test in a high-risk patient Doing bone density test when it is unlikely to change clinical management	Healthy 67-year-old woman not tested Healthy 35-year-old woman is tested
Quality control	Failure to follow manufacturers’ recommendations for system maintenance and phantom measurement Failure to identify and correct significant change in calibration Failure to do precision assessment and calculate LSC	Phantom scanning never done Results of phantom scanning not reviewed or instrument servicing not requested when calibration has changed It is not possible to quantitatively compare BMD tests if LSC is not known
Acquisition	Improper patient positioning Wrong scan mode Invalid skeletal site Artifacts not removed from scanned area Incorrect demographic information	Spine not parallel to edges of DXA table or hip not sufficiently internally rotated Scan mode may alter BMD and is manually or automatically selected, depending on the instrument used BMD measured at hip with total hip replacement Spine scanned when patient is wearing underwired bra or has belly button ring in place Man entered as woman, or incorrect age used
Analysis	Failure to review and correct improper default identification of bone edges and regions of interest Incorrect labeling of vertebral bodies	Computer includes large osteophyte in area of measured spine Helpful markers are the iliac crest, usually at the L4–L5 interspace, and lowest set of ribs, usually at T12
Interpretation	Incorrect application of WHO diagnostic T-score criteria and ISCD Official Positions Invalid BMD comparison Stating that bone has been lost when there is only one BMD test Fracture risk incorrectly represented	Reporting T-scores in a healthy premenopausal woman and applying the WHO diagnostic criteria may result in faulty assessment of fracture risk LSC not known, different instruments used, different bone area scanned, different labeling of vertebral bodies, left hip compared with right hip, comparing T-scores instead of BMD, different scan modes Bone loss can only be identified when serial BMD tests have been done and the LSC is known Expressing fracture risk as relative risk will overestimate fracture probability if the comparator population is at low fracture risk

This is not a complete list but is representative of typical mistakes made in clinical settings. Abbreviations: BMD, bone mineral density; DXA, dual-energy X-ray absorptiometry; ISCD, International Society for Clinical Densitometry; LSC, least significant change.