Medroxyprogesterone acetate enhances the spinal bone mineral density response to oestrogen in late post-menopausal women.
OBJECTIVE
The relative contributions of administered oestrogen and progestin to protection of the post-menopausal skeleton remain unclear. We have compared the effect on spinal bone mineral density of continuous combined oestrogen/medroxyprogesterone therapy with that of unopposed oestrogen in late post-menopausal women.


METHODS
Observational study.


METHODS
Seventy-three osteoporotic post-menopausal women attending the Auckland Hospital Bone Clinic. Twenty-three hysterectomized women were treated with unopposed oestrogen (0.625 mg oral conjugated oestrogens daily), and 50 non-hysterectomized women were treated with continuous combined oestrogen/medroxyprogesterone therapy (5 mg medroxyprogesterone acetate and 0.625 mg oral conjugated oestrogens daily).


METHODS
Baseline and one-year measurements of lumbar spine bone mineral density were performed using dual-energy X-ray absorptiometry.


RESULTS
After one year of therapy, spinal bone mineral density increased by 6.6% (95% confidence interval 5.6-7.6, P < 0.001 vs baseline) in the combined oestrogen/medroxyprogesterone therapy group, compared to 4.0% (CI 2.4-5.7, P < 0.001 vs baseline) in the unopposed oestrogen group (difference between means 2.6% (CI 0.8-4.4, P < 0.01).


CONCLUSIONS
In osteoporotic post-menopausal women, one year of continuous combined oestrogen/medroxyprogesterone therapy is associated with a 65% greater increment in spinal bone mineral density than is observed in response to unopposed oestrogen. The prescription of combined oestrogen/progestin therapy should be considered in osteoporotic post-menopausal women who have undergone hysterectomy, in order to maximize the skeletal protection provided by hormone replacement therapy.
Grey
A
A
Department of Medicine, University of Auckland, New Zealand.
Cundy
T
T
Evans
M
M
Reid
I
I
D015502:Absorptiometry, Photon; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000187:drug effects*; D004359:Drug Therapy, Combination; D004966:Estrogens, Conjugated (USP) / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007044:Hysterectomy; D008159:Lumbar Vertebrae / Q000187:drug effects / Q000502:physiology; D017258:Medroxyprogesterone Acetate / Q000627:therapeutic use*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy* / Q000503:physiopathology
D004966:Estrogens, Conjugated (USP); D017258:Medroxyprogesterone Acetate