Dual-photon Bone Densitometry in Normal Australian Women: a Cross-sectional Study

Osteoporosis is a major health problem in Australia, as it is in most Western societies. Bone mineral density in the spine and femoral neck are accurate indicators of osteopenia and thus useful indicators of the risk of a fracture. Dual-photon absorptiometry is a non-invasive technique that allows the accurate quantitation of bone mineral density in the lumbar vertebrae and proximal femur with a low radiation exposure. The increasing availability of this technique dictates the requirement for "normal" ranges and quality control. We report here lumbar vertebral and proximal femur bone mineral density as measured by dual-photon absorptiometry in 179 normal Australian women. Forearm bone mineral content in these subjects, as measured by single-photon absorptiometry, is also presented. There was a relative stability of lumbar bone mineral density and forearm bone mineral content before the menopause, after which there was an age-related decline. On the other hand, bone mineral density at all three sites in the proximal femur showed an age-related decline throughout adult life. Intraoperator variability in calculated bone mineral density did not exceed 2.3%. The requirement for correct positioning of the patient is illustrated. The data allow statistical analysis and the development of normal ranges. They provide an Australian base against which individual patient values can now be compared.