Dissertation/Thesis Abstract

The impact of adiposity on estrone, estradiol, testosterone and sex hormone binding globulin in peripubertal females
by Baker, Erin R., Ph.D., University of Cincinnati, 2010, 151; 3426178
Abstract (Summary)

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.

Indexing (document details)
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
Subjects: Biostatistics, Epidemiology
Keywords: Adiposity, Body mass index percentile, Estradiol, Estrone, Fat mass, Peripubertal females, Puberty, Sex hormone binding globulin, Testosterone, Waist to hip ratio
Publication Number: 3426178
ISBN: 978-1-124-26367-0
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