Definition of Osteoporosis by Bone Density Criteria in Men: Effect of Using Female Instead of Male Young Reference Data Depends on Skeletal Site and Densitometer Manufacturer

Whether to use young male or young female reference data to calculate bone mineral density (BMD) T-scores in men remains controversial. The third National Health and Nutrition Examination and Survey (NHANES III) data show that the mean and standard deviation of femoral neck and total hip BMD is greater in young men than young women, and therefore differences in T-scores at these sites using NHANES III female vs male norms becomes less as BMD decreases. In contrast, manufacturer-specific reference databases generally assume similar standard deviations of BMD in men and women. Using NHANES III reference data for the femoral neck and total hip, respectively we found that men with T-scores of −2.5 when young male norms are used have T-scores of −2.4 and −2.3 when young female norms are used. Using manufacturer-specific reference data, we found that men with T-scores of −2.5 when young male norms are used at the femoral neck, total hip, lumbar spine, or one-third of the forearm would have T-scores ranging from −2.4 to −0.4 when young female norms are used, depending on skeletal site and densitometer manufacturer. The change of proportions of men diagnosed with osteoporosis when young female norms are used instead of young male reference data differs substantially according to skeletal site and densitometer manufacturer.