Bone densitometry in the diagnostic approach of metabolic bone disease

Bone mineral density (BMD) measurements using dual X-ray absorptiometry(DXA) are currently used to detect the presence of osteoporosis and to assess the risk of fracture. The average Lifetime risk of osteoporotic fracture in women is about 40% at the age of 50 years and approximatively doubles for each standard deviation decrease in BMD. DXA techniques are useful for screening programme: its ability and cost-benefit ratio increases when BMD is measured Ln people who exhibit many other risk factors. Although site specific measurements may be needed in some particular clinical situations, BMD measurements at any of the routinely assessed skeletal sites can be used to stratify people on the basis of their overall fracture risk. In the early menopause a great number of patients with osteoporosis may be detected assessing L2-L4 BMD, while at age 80 more patients are correctly classified using femur-BMD. Other than a diagnostic and prognostic tool, BMD measurements may be used to monitor the response to anti-osteoporotic treatments. Whole body BMD is the technique more reproducible and so it is the method of choice to gauge the longitudinal effects of the therapy.