Decrease in bone level of 1,25-dihydroxyvitamin D in women over 45 years old.

The most active metabolite of vitamin D is 1,25-dihydroxyvitamin D [1,25(OH)2D]. Its level in the bone may play a role in the pathogenesis of metabolic bone diseases such as osteoporosis. To assess this, and to see whether there is correlation between serum and bone levels, we studied serum and bone samples taken from 43 patients (18 men and 25 women) undergoing different orthopedic procedures. Patients were studied according to sex and age groups (less than 45 years, 46-60 years, greater than 61 years). Serum level of 1,25(OH)2D was found to be 29.7 +/- 2.61 pg/ml (mean +/- SEM) for women, 32.2 +/- 3.86 pg/ml for men, and 30.7 +/- 2.18 pg/ml for the group as a whole. No significant statistical differences were found among age subgroups in either sex or between sexes. Bone level of 1,25(OH)2D was found to be 31.5 +/- 4.46 pg/g for women, 26.5 +/- 3.06 pg/g for men, and 29.4 +/- 2.81 pg/g for the entire group. No significant statistical difference was found between the age subgroups for men. However, the level of 1,25(OH)2D was found to be higher in the group of younger women (less than 45 years) compared with the older women (46-60 years and greater than 61 years) (P less than 0.005).