Early postmenopausal bone loss is prevented by estrogen and partially by 1alpha-OH-vitamin D-3: Therapeutic effects of estrogen and or 1 alpha-OH-vitamin D-3

A total of 79 Japanese women who were within 5 years of menopause were rand omly assigned 1 alpha-hydroxyvitamin D-3 [1 alpha(OH)D-3] 1.0 mu g/day, con jugated estrogens 0.625 mg/day, a combination of both, or control (no treat ment). Lumbar spine and proximal femur bone mineral density (BMD) and bioch emical indices were monitored over 2 years. In the 1 alpha(OH)D-3-treated,g roup, there was a nonsignificant decrease in lumbar spine BMD compared with controls, and no significant loss in the femoral neck compared with contro ls. In the estrogen-treated group, there was a nonsignificant increase in s pine BMD (+2.17% in the first year and +1.71% in the second year), and no l oss in femoral neck BMD. The combination of conjugated estrogens +1 alpha(O H)D-3 was more effective in increasing BMD in the spine (+3.68% in the firs t year and +3.63% in the second year) and femur (+2.56% in the first year a nd +4.44% in the second year) BMD. There was a significant difference in lu mbar spine BMD in both the first and second years between the combination-t reated group and the 1 alpha(OH)D-3-treated and control groups (P < 0.01). Serum osteocalcin (OC) significantly decreased in the combination-treated g roup (-23.8% in the first year) and the estrogen-treated group (-37.6% and -41.2% at 6 and 18 months, respectively), and serum alkaline phosphatase (A lp) decreased significantly in the first year in the combination-treated (- 31.5%), estrogen-treated (-27.3%), and 1 alpha(OH)D-3-treated (-7.9%) group s, whereas serum OC increased (+45.4% in the first year) in women without t reatment. The results of this study indicate that early postmenopausal bone loss in the femoral neck is prevented by conjugated estrogens, 1 alpha(OH) D-3, or bath, whereas bone loss in the spine is not prevented by 1 alpha(OH )D-3. Estrogen proves effective in preventing early postmenopausal bone los s by markedly inhibiting bone turnover. Moreover, a synergistic bone-sparin g effect can be expected when estrogen is administered concomitantly with 1 alpha(OH)D-3 rather than when used alone.