Bone loss in elderly women prevented by ultralow doses of parenteral 17β-estradiol

OBJECTIVES: Our purpose was to assess whether an ultralow dose of parental estradiol, aimed for treatment of vaginal atrophy, affects bone metabolism and bone density. STUDY DESIGN: Thirty healthy women ≥ years old were randomly assigned to a 6-month treatment with either an ultralow dose of parenteral estradiol (7.5 μg/24 hours) delivered by vaginal rings or no treatment in the proportion 2:1. RESULTS: Forearm bone density increased in estradiol users by 2.1% (95% confidence interval 0.4 to 3.8, p = 0.008), contrasting to a decrease in nonusers of –2.7% (95% confidence interval –5.9 to 0.4, p = 0.077). In analysis of variance the changes in the two study groups differed significantly (p = 0.0004). Consistently, serum alkaline phosphatases, bone-specific alkaline phosphatases, and osteocalcin concentrations decreased in the treatment group (8%, p = 0.019; 14%, p = 0.0006; and 9%, p = 0.02, respectively), suggesting reduced bone turnover. No significant changes were found in nonusers. CONCLUSION: Ultralow doses of estradiol may potentially prevent bone loss in women ≥ years old. (Am J Obstet Gynecol 1997;177:115-9.)