RACIAL DIFFERENCES IN CIRCULATING SEX STEROIDS: MECHANISMS AND EFFECT ON BONE

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. The purpose of this study is to characterize the steroid level profile throughout the menstrual cycle in Black females compared to White females, and to monitor the effects of obesity and race on sex steroid levels and bone mineral density and architecture. There appears to be strong and increasing evidence that there are fundamental differences in circulating sex steroid levels, which contribute to a multitude of end organ changes in Blacks. We propose to document these in greater detail, above all accounting for differences in obesity between racial groups. Additionally there has been nothing but descriptive studies to date, and little exploration of potential mechanisms. In this study 200 normally cycling females of Black and White origin will be studied. We will intensively study the menstrual cycle with daily urinary collections, and for one cycle blood draws and ultrasound documentation of follicular development. We will characterize circulating sex steroid during the course of the menstrual cycle. Additionally we will examine body composition and bone mineral density and architecture in this group. We will also collect serum so that we can look at insulin resistance, cardiovascular risks, DNA, and serum for proteomics in this cohort. We propose to establish normative data for sex hormone levels in Black women with a history of regular menstrual cycles and compare these with their White counterparts. Three consecutive menstrual cycles will be studied in women who are of normal body weight, height, and BMI. These data will serve as our primary outcome. We also propose to measure sex hormone levels in obese Black and White women, collect serum for the future so we can look at insulin resistance, cardiovascular risks, DNA and serum proteomics, and in all groups bone mineral density and architecture will be calculated.