A double-blind randomised controlled trial of the effects of medroxyprogesterone acetate on bone density of women taking oestrogen replacement therapy.

Objective: To assess the effects of medroxyprogesterone acetate on bone density in women who have had a hysterectomy.

Design: Randomised, double-blind, placebo-controlled trial of medroxyprogesterone acetate 10 mg, 20 mg or placebo as an adjunct to oestrogen therapy.

Participants: One hundred and twenty-three women, aged 18 to 45 years and currently receiving daily oestrogen, who presented at a university-based rheumatology practice.

Interventions: The women were randomly assigned to receive either medroxyprogesterone acetate 10 mg, 20 mg or placebo daily beginning on day 15 of each month for one year. Forty-one women were randomised into each group.

Main Outcome Measure: The primary outcome measurement was the percentage of change from baseline in bone mineral density of the lumbar spine (L2-L4). Secondary outcome measures included differences in femoral neck bone density, cholesterol and triglyceride levels between groups.

Results: At one year, change in bone mineral density did not differ between either the treatment or placebo groups. Medroxyprogesterone acetate 20 mg and 10 mg led to statistically significant reductions in very low density lipoprotein cholesterol, total triglycerides, and very low density lipoprotein triglycerides when compared with placebo. Medroxyprogesterone acetate 20 mg also led to a statistically significant reduction in high density lipoprotein cholesterol, high density lipoprotein-2 cholesterol, and high density lipoprotein-2 triglycerides.

Conclusions: Medroxyprogesterone acetate at either dose as an adjunct to oestrogen did not improve bone mineral density at one year when compared with placebo. Medroxyprogesterone acetate 10 mg may not adversely affect lipids. Medroxyprogesterone acetate 20 mg, however, did reduce high density lipoprotein cholesterol and therefore may increase cardiovascular risk.