The effect of oestradiol implants on regional and total bone mass: a three-year longitudinal study

Although there is evidence from cross-sectional studies that percutaneous oestrogen administration protects against menopausal bone loss, few longitudinal data are available. We have examined the effect of 3 years' treatment with percutaneous oestradiol on total body calcium, spinal trabecular bone mineral density and radial bone mineral content in post-menopausal women.

Twenty-nine post-menopausal women, aged 37-55 years, who had undergone hysterectomy and had experienced the onset of menopausal symptoms within the previous 2 years, were studied before and for 3 years during hormone replacement with oestradiol implants, given at approximately 6-monthly intervals.

Total body calcium was measured by prompt gamma neutron activation analysis, spinal trabecular bone mineral density by quantitative computed tomography and radial bone mineral content by single-photon absorptiometry.

There was a significant increase in the mean total body calcium, spinal trabecular bone mineral density and radial bone mineral content over the 3 years of the study. The mean (+/- SEM) percentage change per annum was +2.4% (+/- 0.8) for total body calcium (P < 0.01), +3.3% (+/- 0.6) for spinal trabecular bone mineral density (P < 0.001) and +1.2% (+/- 0.6) for radial bone mineral content (P < 0.05).

Percutaneous oestradiol replacement therapy prevents menopausal bone loss and is associated with a sustained and significant increase in total body calcium, spinal trabecular bone mineral density and radial bone mineral content over a 3-year treatment period. Oestradiol implants thus have skeletal effects comparable to those of oral or transdermal oestrogens.