[Status of bone mineral density after the long-standing application of contraception Depo-Provera]

The objective of this study was to assess bone mineral density (BMD) on a cohort of women who used depot medroxyprogesterone acetate (DMPA) (Depo-Provera) contraception uninterruptedly between 3 and 10 years.

Retrospective study with review of the literature.

Office gynecology Velké Meziříčí; Osteocentrum Brno; Department of Obstetrics and Gynecology, Hospital Nové Město na Moravě.

The study included 21 healthy women aged between 26 and 43 years (the mean age 31 years) who started long-term continual application of depot medroxyprogesterone acetate (DMPA) in contraception (Depo-Provera) (the mean time of using 7 years, range 3-10 years). The women underwent lumbar spine, hip, femoral neck and forearm BMC (g) (bone mass content), BMD (g/cm2)(bone mass density), T-score, PR (%) (peak reference), Z-score, AM (%)(age matched) evaluation using Hologic dual-energy X-ray absorptiometry. Age of women, time of application of Depo-Provera and body mass index (BMI) were collected. Randomly from this cohort of users DMPA (n = 11) were determined levels of serum folicle stimulating hormone (FSH) and estradiol (E2), mostly shortly before next application of DMPA.

At average 7 years of treatment, as compared to baseline, the mean BMD of DMPA users was in total lumbar spine AM (age matched) 96.48%, total hip AM 100%, femoral neck AM 97.62%, total forearm (radius+ulna) AM 99.81%. Concentrations of serum estradiol varied from 94.3-294 pmol/l (25.7-80.1 pg/ml) with average level 190.3 pmol/l(51.9 pg/ml), seen in the early follicular phase.

There are probably several reasons, but not at least, why mean bone loss even after long use of DMPA is low. The loss of BMD is more pronounced during the first 2 years of use DMPA and its fall subsequently gradually stabilises due to new balance between extrinsic and intrinsic factors that influence bone resorption and formation. After the two years bone loss in DMPA users nears under 1% per year and practically copies level of physiological bone loss. Another hypothetical compensation mechanisms of bone remodelling in the hypoestrogenic time during DMPA use may be reason of higher levels of BMD 4-5 years after discontinuing the use of contraceptive injections than that of nonusers (rebound phenomenon).