Early postmenopausal bone loss is prevented by estrogen and partially by 1α-OH-vitamin D3:: Therapeutic effects of estrogen and or 1α-OH-vitamin D3

A total of 79 Japanese women who were within 5 years of menopause were randomly assigned 1 alpha-hydroxyvitamin D-3 [1 alpha(OH)D-3] 1.0 mu g/day, conjugated estrogens 0.625 mg/day, a combination of both, or control (no treatment). Lumbar spine and proximal femur bone mineral density (BMD) and biochemical indices were monitored over 2 years. In the 1 alpha(OH)D-3-treated,group, there was a nonsignificant decrease in lumbar spine BMD compared with controls, and no significant loss in the femoral neck compared with controls. In the estrogen-treated group, there was a nonsignificant increase in spine BMD (+2.17% in the first year and +1.71% in the second year), and no loss in femoral neck BMD. The combination of conjugated estrogens +1 alpha(OH)D-3 was more effective in increasing BMD in the spine (+3.68% in the first year and +3.63% in the second year) and femur (+2.56% in the first year and +4.44% in the second year) BMD. There was a significant difference in lumbar spine BMD in both the first and second years between the combination-treated group and the 1 alpha(OH)D-3-treated and control groups (P < 0.01). Serum osteocalcin (OC) significantly decreased in the combination-treated group (-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 (Alp) 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%) groups, whereas serum OC increased (+45.4% in the first year) in women without treatment. 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 loss by markedly inhibiting bone turnover. Moreover, a synergistic bone-sparing effect can be expected when estrogen is administered concomitantly with 1 alpha(OH)D-3 rather than when used alone.