Objective: To examine the short-term effects of the transdermal contraceptive patch on markers of bone turnover in
young women.
Study Design: Prospective open-label study.
Patients and Methods: Nine healthy premenopausal women volunteered and were prescribed one cycle of the
transdermal contraceptive patch containing 6.0 mg norelgestromin/0.6 mg ethinyl estradiol. Fasting blood samples were
taken at Baseline and then for an additional four consecutive weeks to assess changes in bone formation (bone-specific
alkaline phosphatase; BSAP) and bone resorption (serum collagen type I cross-linked C-telopeptide; SCTX-I).
Results: Compared to Baseline (0.61±0.16 ng•mL-1) SCTX-I was reduced by 40% (0.36±0.10ng•mL-1; P=0.002) after
only one week and tended to remain suppressed by 26-30% (P≤0.11) during the second and third week, returning to
90% of Baseline (0.54±0.15ng•mL-1) after the withdrawal week. Compared to Baseline (25.8±6.8U•L-1) BSAP levels
were 12% (22.8±6.6U•L-1, P=0.486) and 18% (21.2±5.9U•L-1, P=0.249) lower after two and three weeks, respectively,
returning to 94% (24.4±6.2U•L-1) of Baseline values following the withdrawal week.
Conclusions: The transdermal contraceptive patch rapidly reduced bone resorption, but has a delayed and less
suppressive effect on bone formation. Despite the observed reductions, the concentration of bone turnover markers
remained within reference ranges for premenopausal women. Practitioners prescribing hormonal contraceptives to
young women should be aware of the rapid response of bone metabolism to this class of drugs.