Radial and metacarpal bone mineral density and calcaneal quantitative ultrasound bone mass in normal Japanese women.

Nationwide data on bone mass were collected from 33,992 subjects who underwent screenings for osteoporosis at 65 health care centers in 11 prefectures in Japan. Reference values in Japanese women were evaluated by the four convenient methods frequently used for the screening of osteoporosis based on healthy subjects, defined by their medical history. In addition, the prevalence of low bone mass was estimated in subjects 40 years or older by the four methods. Compared with the young normal subjects aged 20-29 years old, bone mass decreased after 30, 40, and 50 year in the calcaneus by quantitative ultrasound densitometry, the radius by dual energy X-ray absorptiometry (DXA), and the metacarpus by computed X-ray densitometer and digital image processing. The prevalence of a T-score <-1 was relatively similar (45.6-65.5% in the fifth decade and 81.3-94.3% in sixth) in each decade among the four methods. However, the use of a T-score </=-2.5 resulted in a marked difference in the prevalence (5.2-23.5% in the fifth decade, and 18. 7-67.9% in the sixth) among the methods. The cutoff value of bone mass at a T-score -2.5 was greater than the lowest quintile value of the fifth decade in radial bone mineral density (BMD), between the lowest quintile values of the fifth and sixth decades in the two metacarpal methods, and less than the value of the sixth decade in the calcaneal Stiffness index.