A prospective study on the effects of depot medroxyprogesterone acetate on trabecular and cortical bone after attainment of peak bone mass

Objective To study the annual change of bone mass in women aged 30–45 years being treated with depot medroxyprogesterone acetate (DMPA) in order to evaluate whether the bone mass depends on the duration of DMPA use or the oestradiol level. Design Prospective longitudinal study over an interval of 12 months. Setting A family planning centre of a university hospital. Patients Thirty-six current users of DMPA. Interventions Injection of 150 mg DMPA every 12 weeks. Measurements Bone mass was measured at the distal radius by peripheral quantitative computed tomography (reproducibility 0.3%). Results Mean annual changes (SD) in trabecular and cortical bone mass were 0.06 (1.6%) [P= 0.8] and −0.26% (0.6) [P < 0.04]. The decrease in cortical bone mass was not significant because the changes were within the precision error of the method used for the measurements. Duration of DMPA use and oestradiol levels were not associated to the bone parameters. Conclusion We did not find a negative impact of DMPA on the bone mass of premenopausal women aged 30–45 years.