Effects of an oral contraceptive (norgestimate/ethinyl estradiol) on bone mineral density in adolescent females with anorexia nervosa: a double-blind, placebo-controlled study

Abstract

Purpose: To evaluate the effect of an oral contraceptive (OC) on bone mineral density (BMD) in adolescent females with anorexia nervosa (AN) or eating disorder not otherwise specified (EDNOS).

Methods: Females 11-17 years of age with AN or EDNOS entered the study. Subjects were randomized equally to treatment with a triphasic OC containing norgestimate (NGM) 180-250 microg and ethinyl estradiol (EE) 35 microg or placebo for 13 28-day cycles. Dual energy x-ray absorptiometry scans (DXA) of the lumbosacral spine (LS) and hip were obtained at baseline and after 6 and 13 cycles.

Results: Demographic characteristics of the 112 subjects (NGM/EE 53; Placebo 59) who received study drug and had at least one on-treatment DXA were similar between groups for age (mean: 15 years in each group) and body mass index (mean: NGM/EE 17.9 kg/m2; Placebo 17.6 kg/m2). At the end of Cycle 6, there was a significant increase in the mean LS BMD in the NGM/EE group compared with placebo (.020 g/cm2 vs. .008 g/cm2; p = .021); however, at the end of Cycle 13 the mean increase in LS BMD in the NGM/EE group compared with placebo was no longer significant (.026 g/cm2 vs. .019 g/cm2, p = .244). There was no significant difference in change in hip BMD between groups. The incidence of adverse events was similar between groups.

Conclusions: In a group of adolescent females with AN or EDNOS, treatment with a triphasic OC for 13 cycles did not have a statistically significant effect on LS or hip BMD.