Oral contraceptive use, bone mineral density, and bone turnover markers over 12months in college-aged females.

Abstract

The purpose of this study was to compare bone mineral density (BMD) and bone turnover markers between combined oral contraceptive (COC) and non-COC users over 12months. COC users (n = 34, age = 19.2 ± 0.5) and non-COC users (n = 28, age = 19.3 ± 0.6) provided serum at baseline, 6months, and 12months. C-terminal telopepetides (CTX) and pro-collagen type 1N-terminal propeptides (P1NP) were determined using ELISA. BMD was measured at the three time points using dual-energy x-ray absorptiometry (DXA). COC users had greater CTX than non-COC users at baseline (18.6 ± 8.2 vs. 13.8 ± 5.3ng/mL, P = 0.021) and 6months (20.4 ± 10.3 vs. 14.2 ± 8.5ng/mL, P = 0.018). Controlling for lean mass, groups were similar in BMD. Over 12months, non-COC users maintained BMD at the spine, while the COC users declined 2.2% in lateral spine BMD (0.773 ± 0.014 to 0.756 ± 0.014g/cm2, P = 0.03) and 0.7% in anterior-posterior spine BMD (1.005 ± 0.015 to 0.998 ± 0.015g/cm2, P = 0.069). Non-COC users increased in BMD of the whole body over 12months (P < 0.001) while COC users had no change. Women who began COCs within 4years after menarche had lower BMD at the hip and whole body. Women taking very low dose COCs (20 mcg ethinyl estradiol, EE) significantly declined in CTX, P1NP, and lateral spine BMD in comparison to participants using low dose COCs (30/35 mcg EE). College-aged women who did not use COCs increased BMD of the whole body, while COC users had elevated bone turnover, declines in spinal BMD, and lack of bone acquisition of the whole body over 12months. Young females who initiate COC use early after menarche may experience skeletal detriments.