[The significance of bone mineral density measurement of premenopausal women].

We examined the starting age for measuring bone mineral density (BMD) in premenopausal women to detect osteopenia as soon as possible. BMD of the second to fourth lumbar spine vertebrae was measured by dual-energy X-ray absorptiometry to determine normal values for 500 healthy premenopausal women (aged from 17 to 55). We found the rate for low BMD premenopausal women, whose BMD was under the peak bone mass-2SD. And we compared normal BMD women with low BMD women with reference to menstrual history, obstetrical history, and life style, by means of a questionnaire. The peak bone mass of premenopausal women was reached between 35 and 39 years of age (1.059 +/- 0.097g/cm2). The low BMD rate was 7% in all premenopausal women, and increased to 13.5% at from 45 to 49 years. On the other hand, it was only from 5.7 to 7.4% even at from 20 to 29 years. There was the positive correlation between BMD and the body mass index (BMI). There was no statistically significant difference between the low BMD women and the normal BMD women in menstrual history, obstetrical history or life style (parity was 1.7 +/- 1.6 and 1.1 +/- 1.2, respectively, p < 0.05). We concluded that premenopausal women should have their BMD measured after aged 45, and be measured once from 20 to 40 years of age if possible.