Inhibitory effect of obesity on gonadotropin, estradiol, and inhibin B levels in fertile women.
OBJECTIVE
To examine whether obesity and insulin resistance have an independent effect on the gonadotropin, estradiol, and inhibin B serum levels and follicle count in the early follicular phase of fertile women with a wide range of BMI and without signs of hyperandrogenism.


METHODS
Twenty-two overweight and obese (BMI > or =25.0 kg/m(2)) women and 10 normal-weight (BMI <25.0 kg/m(2)) women, all having apparently normal fertility, were studied. Serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, inhibin B, and insulin, level of insulin resistance (estimated by homeostasis model assessment for insulin resistance), and follicle count were measured during the early follicular phase (Days 2 to 5 of the menstrual cycle).


RESULTS
Overweight women showed lower FSH (p < 0.001), LH (p < 0.001), and inhibin B (p < 0.05) levels compared with normal-weight women, whereas estradiol concentrations and follicle count were not significantly different between the two groups. When normal-weight and overweight women were examined as a group and multiple regression analyses were performed, estradiol showed a negative association with BMI (or waist circumference) (p < 0.05) and a positive correlation with LH (p < 0.05) and FSH (p < 0.05); inhibin B maintained a positive association only with estradiol (p < 0.05); and FSH and LH showed a negative correlation with BMI (or waist circumference) (p < 0.001 and p < 0.01, respectively).


CONCLUSIONS
Overweight and obese fertile women have lower FSH, LH, inhibin B, and estradiol levels in the early follicular phase, with a possible direct inhibitory effect of body mass on gonadotropin and estradiol production, independently of age, insulin (concentrations and sensitivity), and other hormones. By contrast, the number of ovary follicles does not seem to be influenced by insulin and body mass in these patients.
De Pergola
Giovanni
G
Section of Internal Medicine, Endocrinology, and Metabolic Disease, Department of Emergency and Organ Transplantation, Bari, Italy. g.depergola@endo.uniba.it
Maldera
Simona
S
Tartagni
Massimo
M
Pannacciulli
Nicola
N
Loverro
Giuseppe
G
Giorgino
Riccardo
R
D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D005498:Follicular Phase / Q000097:blood / Q000502:physiology; D006062:Gonadotropins / Q000097:blood*; D006801:Humans; D007247:Infertility, Female / Q000097:blood* / Q000209:etiology; D007265:Inhibins / Q000097:blood*; D007333:Insulin Resistance; D007986:Luteinizing Hormone / Q000097:blood; D009765:Obesity / Q000097:blood* / Q000378:metabolism / Q000503:physiopathology; D006080:Ovarian Follicle / Q000502:physiology; D012098:Reproduction / Q000502:physiology
D006062:Gonadotropins; C422364:inhibin B; D004958:Estradiol; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone