Bone accretion in adolescents using the combined estrogen and progestin transdermal contraceptive method Ortho Evra: a pilot study.

OBJECTIVE: To date there are no data regarding the effect of the transdermal combined estrogen and progestin contraceptive Ortho Evra on bone mineral content (BMC) and bone mineral density (BMD). We examined the effects of transdermally delivered ethinyl estradiol and norelgestromin on whole body (WB) BMC and BMD of the hip and lumbar spine (LS) of adolescent girls. METHODS: In a matched case-control study girls (n = 5) who applied Ortho Evra for days 1-21 followed by days 22-28 free of medication for 13 cycles (about 12 months) were compared with 5 age- and ethnicity-matched control girls. Evaluations of calcium intake; bone-protective physical activity; bone densitometry (DXA QDR 4500A Hologic); bone formation markers serum osteocalcin (OC) and bone-specific alkaline phosphatase (BAP); bone resorption marker urinary N-telopeptide (uNTX); insulin growth factor-1 (IGF-1); and sex hormone binding globulin (SHBG) were carried out at initiation 6 months and 12 months. Changes from baseline were compared using mixed models adjusting for follow-up comparisons using the Holm Test (sequential Bonferroni). RESULTS: There were no significant differences (SD) between groups at baseline in age gynecologic age WBBMC hip BMD and LSBMD. Girls on Ortho Evra did not change significantly in WBBMC (12-month mean increase 0.2% +/- 0.8%) whereas controls did (3.9% +/- 1.8% P < or = .001 adjusted P = .002) with SD between the 2 groups (P = .007 adjusted P = .036). Adolescents on Ortho Evra did not change significantly in hip BMD (12-month mean increase 0.5% +/- 0.6%) whereas controls did (2.7% +/- 0.6% P < or = .001 adjusted P = .004) with SD between the 2 groups (P = .024) prior to adjustment for multiple comparisons but no SD after adjustment (P = .096). Similarly although the increase in LSBMD within the control group after 12 months (mean increase 2.8% +/- 1.0%) was statistically significant (P = .009 adjusted P = .044) the change within the treatment group (12-month mean increase 0.8% +/- 0.8%) was not. However percent LSBMD changes after 12 months did not significantly differ between the 2 groups before or after adjustment for multiple comparisons. Calcium intake and bone-protective physical activity did not significantly predict BMC and BMD changes of study participants. There was a significantly greater increase in SHBG levels in the treatment group after 6 months (P = .003 adjusted P = .013) and 12 months (P < or = .001 adjusted P < or = .001) than in controls. Changes in levels of OC BAP uNTX and IGF-1 were not significantly different between the 2 groups. CONCLUSIONS: Ortho Evra use attenuates bone mass acquisition in young women who are still undergoing skeletal maturation. This attenuation may be attributed in part to increased SHBG levels which reduce the concentrations of free estradiol and free testosterone that are available to interact with receptors on the bone. Clinical implications remain to be determined in studies with a larger number of adolescents. Copyright 2010 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.