Walsh JS et al. (2008) Effects of depot medroxyprogesterone acetate on bone density and bone metabolism before and after peak bone mass: a case–control study. J Clin Endocrinol Metab [doi:10.1210/jc.2007-2201]

Several studies have linked depot medroxyprogesterone acetate (DMPA) use with reduced BMD. Walsh and colleagues' case–control study assessed whether this BMD deficit is age-specific and/or site-specific, and examined the effects of DMPA on markers of bone turnover and hormone levels.

The study included 50 white women aged 18–25 years who began DMPA use before age 20 years (before peak bone mass was attained), and 50 white women aged 35–45 years who began DMPA use after age 34 years (after peak bone mass was attained). DMPA users were paired with controls matched for age, height, BMI and smoking status.

Compared with controls, BMD was decreased at the lumbar spine (–5.6%, P <0.05) and hip (–5.2%, P <0.05) in DMPA users aged 18–25 years only. There was no difference in forearm BMD between DMPA users and controls in either age-group. Regardless of age, serum levels of propeptide of type I procollagen and N-terminal telopeptide of type I collagen (markers of bone turnover) and insulin-like growth factor 1 were significantly higher in DMPA users than controls (P <0.05), whereas levels of estradiol were significantly lower in DMPA users than controls (P <0.001).

The authors conclude that DMPA is associated with a site-specific BMD deficit in users who have not attained their peak bone mass, and that estrogen deficiency is the main mechanism of increased bone turnover. Further study is needed to determine whether the BMD deficit is reversible in young DMPA users.