IMPACT ON BONE BY DIFFERENT LEVELS OF ESTROGEN IN ORAL CONTRACEPTIVE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。口服避孕药通常会抑制内源性雌激素的产生，因此在青少年中一个更重要的临床问题是雌激素的剂量与最佳骨生长和矿化有关。这项新的试点研究的目的是比较60名年龄在12 - 18岁之间选择口服避孕药进行节育的少女在两年内的骨密度。他们将被随机分配接受Loestrin （20 mcg炔雌醇，0.1 mg去甲地酮）或Ortho 1/35。骨密度结果也将与从同一诊所招募的非激素对照组的结果进行比较。符合条件的受试者将接受启动激素避孕的常规程序，包括简短的身体检查和（通常）骨盆检查。每半年到GCRC进行一次门诊，通过DEXA测量骨密度，人体测量身体成分，并完成一份自我报告的钙摄入量和运动问卷。将获得血液和尿液样本，以评估维生素D、循环雌二醇水平以及骨代谢的生化指标。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Oral contraceptives generally suppress endogenous production of estrogen, so a more clinically important issue in adolescents is what dose of estrogen is associated with optimal bone growth and mineralization. The purpose of this new pilot study is to compare bone mineral density over two years in 60 adolescents girls, aged 12 - 18 years, who choose oral contraceptives for birth control. They will be randomized to receive either Loestrin (20 mcg ethinyl estradiol, 0.1 mg norethidrone) or Ortho 1/35. Bone mineral density results will also be compared with those from a non-hormonal control group recruited concurrently from the same clinic sites. Eligible subjects will undergo the routine procedure for initiating hormonal contraception, including a brief physical and (usually) a pelvic examination. A semi-annual outpatient visit in the GCRC for measurement of bone mineral density by DEXA, anthropometric measurements for body composition and complete a self-report calcium intake and exercise questionnaire. Blood and urine samples will be obtained to assess vitamin D, circulating levels of estradiol plus biochemical markers of bone metabolism.