Normative data of bone mineral density in an unselected adult Austrian population

There is increasing evidence that correct interpretation of bone mineral density (BMD) measurements by dual energy X-ray absorptiometry (DEXA) requires a population-specific reference range. We therefore collected data on age-related BMD in a random sample of the normal adult Austrian population to establish an appropriate normative database.

We measured BMD by DEXA at five different skeletal sites in 1089 subjects, i.e. 654 females and 435 males, aged between 21-76 years, who had been recruited by 17 centres across Austria.

Age-related bone loss was observed until age 65 years with significant changes at the lumbar spine (r = -0.23), total hip (r = -0.07), trochanter (r = -0.10), femoral neck (r = -0.30) and Ward's triangle (r = -0.40) in the women but only at the femoral neck (r = -0.23) and at Ward's triangle (r = -0.40) in the men. When we calculated T scores from the BMD data of the young normal adult study population and used the T score set points according to the WHO classification of osteopenia and osteoporosis, we found that, depending on the skeletal site measured, 7.6-27.4% of the women and 16-41% of the men in our study group had low bone mass, whereas 0.6-2.7% of the female and 0.2-1.0% of the male study population were osteoporotic. However, osteoporosis was indicated in 4-9-fold more females and 5-15-fold more males when we based our estimates on the normative data provided by the manufacturers of the DEXA systems.

Our data underscore the importance of using a population-specific reference range for DEXA measurements to avoid overdiagnosis of osteoporosis.