Bone density in women: a modified procedure for measurement of distal radial density.

This is a cross-sectional study of bone densitometry in greater than 700 normal healthy white women ranging in age from 18 to 98 years. A modified procedure for single-photon bone density analysis of the distal radius is described and compared with dual-photon densitometric measurements of the second through fourth lumbar vertebrae. The distal radial site measured was separated from the ulna by 5 mm. This "5 mm" site was characterized according to trabecular and cortical bone content, measurement reproducibility, positioning precision, and the effects of wrist pronation or supination. The radial site demonstrated a bone density loss of less than 0.1%/year for normal women 25-50 years of age, increasing to 0.7%/year after 50 years of age. In contrast to the variability and inconsistency obtained by us and others utilizing the standard "9/10" site, bone loss with age at the new "5 mm" site correlated closely with generalized bone mineral loss of the axial skeleton. We suggest that there is a unique role for single-beam densitometric measurements of the radius, permitting the rapid and relatively inexpensive evaluation of large populations of women without requiring a visit to a medical center. Such a process can select those requiring further evaluation or medical attention.