Seasonal fluctuations in testosterone-estrogen ratio in men from the Southwest United States.
Although controversial, seasonal variations in testosterone have been  observed in several populations of men throughout the world. This finding  might have an impact on screening and treatment of hypogonadism. We examined  the circannual patterns of sex hormones in the Southwest United States. A  prospectively assembled database of almost 11 000 patients in a men's health  practice was used to collect data on testosterone, estradiol, sex  hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH),  luteinizing hormone (LH), and dehydroepiandrosterone-sulfate (DHEA-S). Patient  age, address, and date of visit were recorded. Of note, testosterone-estrogen  ratio (T/E ratio) and free testosterone were calculated values. The data were  grouped by month and by season (3-month intervals beginning with June, July,  and August as summer). Analysis of variance was used to compare hormone levels  between seasonal and monthly data sets, with P < .05 regarded as  statistical significance. Statistically significant differences in estradiol  (P = .02), T/E ratio (P < .01), FSH (P = .02),  and SHBG (P < .01) were observed between seasons. Peak-to-trough  variations were as follows: 6% for estradiol, 16.5% for T/E ratio, 11.0% for  FSH, and 11.6% for SHBG. The T/E ratio peaked in the spring and was at its  nadir in the fall. No differences in testosterone (P = .21), LH  (P = .25), free testosterone (P = .08), and DHEA-S  (P = .11) were observed. Statistically significant evidence of  variation in estradiol and T/E ratio were identified in the men included in  this study. Although this is consistent with seasonal body habitus changes,  physical activity levels, and hypothesized hormonal patterns, the variability  reported in the literature makes further trials covering a broader geographic  region important to confirm the findings.
Scott Department of Urology, Baylor College of Medicine, Houston, Texas 77030, USA.
Daniel J
DJ
Moskovic
Michael L
ML
Eisenberg
Larry I
LI
Lipshultz
D000368:Aged; D004958:Estradiol / Q000097:blood*; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012621:Seasons; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D015206:Southwestern United States; D013739:Testosterone / Q000097:blood*; D014481:United States
D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone