CALCIUM KINETICS IN PREGNANT AND LACTATING ADOLESCENTS

在美国，青少年怀孕是一个严重的问题。 这一群体中存在特殊的营养问题，以确保 胎儿和成长中的人都能满足最佳的营养需求。 青春期。怀孕的额外营养需求可能是 当母亲尚未完成她的线性生长时，主要关注的问题 还没有完全达到她的峰值骨量。建议的目的是 这项研究是为了解决怀孕和哺乳对 钙吸收效率和骨钙沉积速率 青少年非西班牙裔白人和非西班牙裔黑人的吸收 年龄在11-17岁之间的女孩。每组15名女孩 打算母乳喂养婴儿的人将参加一项 旨在解决效率问题的纵向钙动力学研究 钙吸收率和骨钙转换率 妊娠晚期(怀孕34-36周)及期间 哺乳期(产后1-2个月)。所有青少年都将接受筛查 对于哺乳开始前的积极预测 这项研究。在每一项运动研究中，女孩将被允许进入总医院 约翰·霍普金斯医院的临床研究部。年的上午 每项研究中，女孩们都会喝下一杯含有马厩的牛奶 钙同位素(46Ca)，早餐后补充第二个稳定的钙 同位素(42Ca)将被静脉注射。定时血样 将在同位素剂量后的8小时内获得，并且 将进行完整的24小时尿液采集。额外的斑点尿 每项同位素研究后将收集5天的样本。至 解决怀孕和哺乳期的荷尔蒙反应，促降钙素 在每项研究中将使用空腹血液来测量荷尔蒙 样本。骨钙沉积和骨吸收的速率 这些生理变化将通过使用多个隔室来确定 模特儿。这些研究将提供有关 钙吸收和骨钙的生理性改变 发生的营业额，以支持增加的钙需求 青春期与妊娠和哺乳期的钙需求。

Adolescent pregnancy is a significant problem in the United States. Special nutritional concerns are present in this group to insure that optimal nutritional needs can be met by both the fetus and the growing adolescent. The additional nutritional demands of pregnancy may be of primary concern when the mother has not yet completed her linear growth and has not full achieved her peak bone mass. The aim of the proposed study is to address the impact of pregnancy and lactation on the efficiency of calcium absorption and rates of bone calcium deposition and resorption in adolescent non-Hispanic white and non-Hispanic black girls between the ages of 11-17 years. Fifteen girls from each group who intend to breastfeed their infants will participate in a longitudinal calcium kinetic study designed to address the efficiency of calcium absorption and rates of bone calcium turnover during both the third trimester of pregnancy (34-36 weeks of gestation) and during lactation (1-2 months post partum). All adolescents will be screened for positive predictors of lactation performance prior to the start of the study. In each kinetic study, girls will be admitted to the General Clinical Research Unit at Johns Hopkins Hospital. On the morning of each study, girls will consume a glass of milk containing a stable calcium isotope (46Ca), and following breakfast a second stable calcium isotope (42Ca) will be administered intravenously. Timed blood samples will be obtained for eight hours following the isotope dosing, and a complete 24 hour urine collection will be made. Additional spot urine samples will be collected for 5 days following each isotope study. To address the hormonal response to pregnancy and lactation, calcitropic hormones will be measured during each study using a fasting blood sample. Rates of bone calcium deposition and resorption in response to these physiological changes will be determined using multicompartmental modeling. These studies will provide novel information on the physiological alterations in calcium absorption and bone calcium turnover which occur to support both the increased calcium demands of adolescence and the calcium demands of pregnancy and lactation.