Regional variations in bone mineral density as assessed with dual-energy photon absorptiometry and dual x-ray...

Total-body, lumbar spine, and hip bone mineral density (BMD) scans were obtained in postmenopausal women to examine regional variations in mineralization of trabecular bone. One hundred ninety-nine patients were studied with dual-energy photon absorptiometry (DPA) and/or dual x-ray absorptiometry (DXA). Comparison of BMD at the different sites showed statistically significant correlations (P < .001) among all the sites; however, variations between sites were observed in many patients. Total-body measurements were within normal limits as defined by the system software in 90% of patients with substantial bone mineral loss in the spine or hip. Lumbar spine measurements calculated from the total-body scan differed from the direct measurements by an average of 10% (DPA) and 12% (DXA). These results suggest that site-specific measurements are required to assess regional osteopenia. While total-body scans may be precise and offer the advantage of total-body composition determination, BMD values derived from total-body scans cannot currently replace direct measurements.