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 .
Oestrogen replacement therapy for prevention of osteoporosis after oophorectomy.
The value of oestrogen therapy in the prevention of osteoporosis  after oophorectomy was assessed in 114 middle-aged women who participated in a double-blind controlled trial of mestranol in an average daily dose of 23 mug . The skeletal response to treatment was measured by a photon absorption technique . Where treatment was started within two months of operation subsequent bone mineral loss was prevented . Treatment started three years after oophorectomy caused a highly significant increase in bone mineral content . When treatment was delayed for six years mestranol failed to prevent subsequent bone mineral loss with age . These effects occurred independently of the associated humoral changes in calcium and phosphorus homoeostasis . Mestranol in this dosage appeared to be relatively safe , but it is too early to evaluate the long-term hazards of such therapy
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 .