CONCLUSION Estrogen with an osteoblast P4R-acting progestin ( EPT ) in these five published RCT provides Level 1 evidence that MPA caused significantly greater annual percent spinal BMD gains than the same dose of ET .
OBJECTIVE To assess whether progesterone ( P4 ) or osteoblast P4 receptor-acting progestin ( P ) contributed to estrogen ( E ) therapy-related  increased areal bone mineral density ( BMD ) in r and omized controlled trials ( RCT ) with direct r and omization to estrogen ( ET ) or estrogen-progestin ( EPT ) therapy .
Effect of progestin therapy on cortical and trabecular bone: comparison with estrogen.
PURPOSE To determine the effect of progestin therapy on bone mineral density in postmenopausal women and to compare its effects to those of estrogen . SUBJECTS AND METHODS A prospect i ve , r and omized clinical trial was performed in 81 postmenopausal women aged 51.7 + /- 4.4 years ( mean + /- SD ) . They were assigned to one of four groups : Provera 20 mg , Premarin 0.6 mg , Premarin 0.3 mg plus Provera 10 mg , and a placebo . In addition , all women received calcium supplementation , if necessary , to a calcium intake of 1,000 mg/day . We used single- and dual-photon absorpiometry , metacarpal radiogrammetry , and computed axial tomography to measure bone mineral density in the total skeleton , spine , radius , and metacarpal . RESULTS Women receiving placebo  lost bone at all sites ( p less than 0.01 ) . The Provera-treated group showed no change in total body calcium , but there were decreases in radial density ( p less than 0.01 ) , metacarpal cortex ( p less than 0.01 ) , and spine density ( p less than 0.01 ) . The Premarin-treated group had an increase in spine density and total body density ( p less than 0.05 ) , but a decrease in radial density ( p less than 0.05 ) . The Premarin-plus-Provera group showed no change in spine density , total body calcium , or radial density but had a decrease in metacarpal cortex ( p less than 0.01 ) . CONCLUSIONS Compared to placebo , Provera reduced the rate of loss in cortical areas of the skeleton , but not in the spine , which contains more trabecular bone . In contrast , Premarin reduced the rate of loss in both cortical and trabecular areas of the skeleton . The low-dose combination of Premarin plus Provera was similar in its effect on bone to that of Premarin alone , suggesting that there may be a synergistic effect of this hormone combination on bone . Serum cholesterol levels decreased with Provera , Premarin , and the combination of both , whereas levels of serum triglycerides increased with Premarin treatment , decreased with the Provera regimen , and were unchanged with the combination therapy . Provera does not adversely affect the lipid profile
CONCLUSION Estrogen with an osteoblast P4R-acting progestin ( EPT ) in these five published RCT provides Level 1 evidence that MPA caused significantly greater annual percent spinal BMD gains than the same dose of ET .
OBJECTIVE To assess whether progesterone ( P4 ) or osteoblast P4 receptor-acting progestin ( P ) contributed to estrogen ( E ) therapy-related  increased areal bone mineral density ( BMD ) in r and omized controlled trials ( RCT ) with direct r and omization to estrogen ( ET ) or estrogen-progestin ( EPT ) therapy .