The age of pubertal onset has been documented to be decreasing as the prevalence of overweight and obesity are climbing. There is mounting evidence that adiposity impacts pubertal timing by influencing levels of estrone, estradiol, testosterone, and sex hormone binding globulin. The effect of fat mass and fat distribution on sex hormone levels is not fully characterized in peripubertal females.
In order to better understand this relationship, longitudinal data from the Growing Up Female study was used in a methods study and an association study. The methods study was performed using Dual X-ray Absorptiometry (DXA) scan data (n=108) as an index measure of total fat mass (FM) to test the concordance of calculated FM using Bland-Altman plots and correlations. The Dezenberg equation for calculating FM was found to be the best method, and was highly correlated to the DXA value (r>0.97), but overestimated, in comparison to the DXA, by 0.70 kg ± 1.45.
The FM calculated by the Dezenberg equation was then used in an association study to evaluate the relationship between FM, body mass index percentile (BMI%tile) and waist to hip ratio (WHR) with levels of estradiol and sex hormone binding globulin. The dataset for the association study consisted of 140 girls with observations from eighteen months prior to breast stage II through six months after onset of breast stage II.
FM, BMI%tile, WHR, along with time relative to breast stage II onset were used to account for variability in log-transformed estradiol in mixed effects linear models for repeated measures. Additional analyses were conducted on subgroups defined by the median values of FM, BMI%tile, and or WHR to illustrate their relationship to estradiol, estrone, testosterone or sex hormone binding globulin.
BMI%tile and WHR by timing relative to the onset of breast stage II interaction had significant associations with estradiol serum concentrations. Timing relative to the onset of breast stage II and FM also were significantly associated with estradiol. Statistically significantly lower levels of estradiol were found in girls with high BMI%tile in comparison to girls with lower BMI%tile and lower WHR. These findings confirm previous reports of breast stage II with low levels of estradiol and extend them with analysis of anthropometric measures.
|Advisor:||Pinney, Susan M.|
|Commitee:||Biro, Frank M., Dietrich, Kim N., Khoury, Jane C.|
|School:||University of Cincinnati|
|Department:||Epidemiology (Environmental Health)|
|School Location:||United States -- Ohio|
|Source:||DAI-B 71/12, Dissertation Abstracts International|
|Keywords:||Adiposity, Body mass index percentile, Estradiol, Estrone, Fat mass, Peripubertal females, Puberty, Sex hormone binding globulin, Testosterone, Waist to hip ratio|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be