DXA bone mineral density in males: retrospective study in real life

The diagnosis of osteoporosis in men remains controversial. Aims of this study were to evaluate the major anthropometric determinants of BMD in a large cohort of male Italian subjects and asses the prevalence of subjects with T-score ≤-2.5 by making use of young male or female BMD reference data.

1,442 Caucasian men aged over 49 years performing a contemporary spine and hip DXA from January 2012 to June 2013 in an out-patient clinics of northern Italy were analyzed. Single and multiple regression analysis was used for correlating BMD to weight and age. The WHO cut-off value (T-score ≤-2.5) was used for the definition of osteoporosis. To compare the prevalence of osteoporosis by adopting male or female BMD reference values the Fisher's exact test was applied.

Age was significantly correlated with spine and neck BMD. The age-BMD correlation was negative for femoral neck while it was positive for the spine. When BMD values were adjusted for body weight the correlation with femoral neck BMD decreased while the positive regression coefficient between spine BMD and age increased. Spine and femoral BMD (both total hip and neck) were positively correlated with body weight. Using BMD male reference values, only 31.2 % of subjects were identified as osteoporotic at least at one site and this proportion was further reduced using female reference data. Spine was able to identify the greatest number of patients with T-score ≤-2.5 (88.7 %) while at femoral sites the proportion was considerably lower (33.6 and 13.8 % for femoral neck and total hip respectively).

In our population, the proportion of male subjects with spine T-score ≤-2.5 is about 25 % of those who were referred for DXA evaluation and this proportion decreases if the female reference data for T-score calculation are chosen. Both spine and femoral neck BMD are strongly and positively related with weight but spine BMD increases with advancing age possibly as a consequence of mechanical and hormonal factors. The capability of spine DXA in identifying men with T-score ≤-2.5 is at its maximum around the fifth decade of life and it decreases later.