Effect of two combinations of low-dose oral contraceptives on adolescent bone mass: A clinical trial with 2 years follow-up

Introduction: Most contraceptive combinations can interfere with the processes of bone formation and resorption. Aim: The aim of this study was to evaluate the effect of 2 combinations of low-dose oral hormonal contraceptives (20 µg ethinyl estradiol [EE]/150 mg desogestrel [COC1] or 30 µg EE/3 mg drospirenone [COC2]) on bone mass acquisition in adolescents over 2 years by means of bone densitometry and measurement of biomarkers of bone remodeling. Methods: Parallel-group, non-randomized controlled clinical trial of 127 adolescents divided into a control group and 2 groups receiving either COC1 or COC2. The participants were submitted to anthropometric assessment and evaluation of secondary sexual characteristics (Tanner criteria) and bone age. Bone densitometry by dual-energy X-ray absorptiometry and measurement of bone biomarkers (bone alkaline phosphatase, osteocalcin, and C-terminal telopeptide) were performed at baseline and after 24 months. Results: No significant differences in the variables analyzed were observed between COC1 or COC2 users and the control group at baseline. After 24 months, non-users had incorporated more bone mass (content and density) than either group of contraceptive users. This negative impact was more pronounced in the COC2 group than in the COC1 group. A significant reduction in the percentage values of bone alkaline phosphatase and osteocalcin was observed in users of oral contraceptives. Conclusion: Bone mass acquisition was compromised in adolescent users of combined hormonal contraceptives. The negative impact was more pronounced in adolescents using contraceptives that contain 30 µg EE/3 mg drospirenone.