Seasonal fluctuations in testosterone-estrogen ratio in men from the southwest United States

Abstract

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 11000 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