(453) Seasonal Variation in Serum Testosterone Levels

Abstract

Abstract Introduction Variation in testosterone levels by season and month have been reported, however results have been inconsistent across studies. Large series are conflicting with reported peaks in June, October, December, and January. Testosterone levels in most of these studies nadir in the spring. The etiology for the variability remains unknown but is likely multifactorial including sunlight exposure, sleep duration, and outdoor temperature. Objective To determine if there is seasonal variability in testosterone levels in a large cohort of men and if this variability may be clinically relevant. Methods Using a single institutional database, testosterone levels were obtained for men ages 18-99 from 2010-2021 who had at least 2 testosterone levels drawn within a 2-year period. Patients who were currently or previously on exogenous testosterone, testosterone stimulating medications, testosterone suppressing medications, and aromatase inhibitors were excluded from the study. Climate data including mean monthly temperature for Miami-Dade County, FL was obtained from the PRISM Climate Group. Minutes of daylight on the fifteenth day of each month was applied as the representative daylight duration for each month. Results There were 3,377 total patients included in the study, there were 9495 total testosterone levels measured with all patients having 2 or more levels. The mean age was 58.8 years old. In the winter the mean testosterone level in the was 422 ng/dl (Figure 1.), the average time of daylight was 682 minutes, and the average temperature was 68 F. In the spring the mean testosterone level was 412 ng/dl, the average time of daylight was 801 minutes, and the average temperature was 78.4 F. In the summer the mean testosterone level was 416 ng/dl, the average time of daylight was 780 minutes, and the average temperature was 83.6 F. In the fall the mean testosterone level in the fall was 417ng/dl, the average time of daylight was 661 minutes, and the average temperature was 75.3 F. Conclusions Our findings suggest seasonal variability in testosterone levels with the highest testosterone levels in the winter, the lowest levels in the spring and a steady increase in testosterone levels in the summer and fall. However, this variation is minor and not likely to be clinically relevant. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: Acerus Pharmaceuticals Consultant, Grant Recipient Boston Scientific Consultant, Grant Recipient Coloplas tConsultant, Grant Recipient Endo Pharmaceuticals Consultant, Grant Recipient Empower Pharmacy Grant Recipient Nestle Health Consultant Olympus Grant Recipient Hims, Inc Advisory Board.