madman
Super Moderator
ABSTRACT
Objective
Seasonal variations in testosterone levels have been reported in some studies, but the results are inconsistent. In this study, we aimed to determine if clinically relevant seasonal variability in testosterone levels exists using a large cohort of men from 2 different institutions, 1 located in an area with seasons (Pittsburgh, PA) and 1 without seasons (Miami, Fla).
Methods
Using 2 institutional databases, testosterone levels were obtained for menages 18-99 from 2010 to 2021 who had at least 2 morning testosterone levels drawn within a 2-year period. All samples were analyzed with liquid chromatography with tandem mass spectrometry. To avoid potential confounding by testosterone-altering medications patients who were currently or previously on exogenous testosterone, endogenous testosterone-stimulating medications, testosterone-suppressing medications, and aromatase inhibitors were excluded from the study.
Results
There were 9495 and 16171 total testosterone levels measured from Miami and Pittsburgh, respectively, with all men having 2 or more levels. There was no statistically significant variation in testosterone levels for the overall cohort in Pittsburgh or Miami, respectively. Additionally, when stratified by age group, no individual groups were found to have significant seasonal variability.
Conclusion
Our findings suggest that although there are differing total testosterone levels between men who reside in 2 different climates, there is no significant variability in testosterone levels between seasons. Therefore, testosterone levels can be checked and interpreted without the need to account for the season during which they were drawn.
Introduction
Awareness of testosterone deficiency and the benefits of initiating hormone replacement for men has increased over the past decade. The prevalence of low testosterone in men over 45 years old is reported to be around 39%.1 It is estimated that nearly 6.5 million men between the ages of 30 and 70 years will have symptomatic testosterone deficiency by the year 2025.2 Low testosterone levels have been shown to be associated with a wide range of issues including erectile dysfunction, cardiovascular comorbidities, diabetes mellitus, osteoporosis, emotional lability, and metabolic syndrome.3 Clinical manifestations of low testosterone may include sleep disturbance, low libido, subfertility, loss of body hair, anemia, reduced strength/physical performance, and increased body fat.4 Testosterone therapy (TT)can correct symptoms associated with testosterone deficiency. Testosterone therapy has the potential to improve libido, erectile function, anemia, increase bone mass density, improved glycemic control, and depressive mood.5,6
For accurate evaluation, clinicians must consider the variations that testosterone undergoes in the human body.7 The diurnal variation of testosterone is well characterized; its levels peak in the morning and decline during the day.8,9 Thus, per American Urological Association guidelines, it is recommended to check morning levels of testosterone for accurate evaluations of testosterone deficiency.10,11 However, there is a lack of consensus on whether there are significant seasonal variations in serum testosterone levels. Several studies have reported possible peaks and troughs across seasons.12-15 Both Dabbs and Lees showed a peak of testosterone levels in winter, while Ballatsella et aland Zornitski et al reported that testosterone peaks in summer. Conversely, other studies concluded that there are no seasonal variations in testosterone.16,17
Our objective was to determine if there is clinically relevant seasonal variability in testosterone levels. We utilized retrospective data of serum testosterone levels in a large cohort of men from 2 different institutions, 1 located in an area with seasons (Pittsburgh, Pa) and 1 without seasons (Miami, Fla). We hypothesized that there would be significant seasonal variability for Pittsburgh, Pa, and that there would be no significant variability for Miami, Fla.
Our study must be interpreted in the context of several limitations. First, we did not assess a variety of potentially significant patient characteristics including ethnicity, body mass index, and medical comorbidities. Second, no information is available about free testosterone, gonadotropins, estradiol, and liver function for our cohort. Thus, we are not able to consider possible seasonal variations of bioavailable testosterone, testosterone-to-estrogen ratio, or the relationship of testosterone with gonadotropins. Third, we did not account for individual exposure to environments outside of their local areas, thus some patients may have had a variable seasonal exposure due to travel. Fourth, there is variability in temperature and daylight hours for the locations that do not have a significant change of seasons (Miami, Fla), which may confound results.
Despite these weaknesses, our study has several strengths. We present findings of seasonal testosterone levels from the largest cohort of men reported thus far, living at 2 separate latitudes, over a long-longitudinal time frame interval, without known testosterone-altering medications, and considered amounts of both daylight and local temperatures. Our findings suggest that although there are differing total testosterone levels between 2 different climates, there is no significant variability in testosterone levels between seasons. Therefore, testosterone levels can be checked and interpreted without the need to account for the season during which they were drawn.
Objective
Seasonal variations in testosterone levels have been reported in some studies, but the results are inconsistent. In this study, we aimed to determine if clinically relevant seasonal variability in testosterone levels exists using a large cohort of men from 2 different institutions, 1 located in an area with seasons (Pittsburgh, PA) and 1 without seasons (Miami, Fla).
Methods
Using 2 institutional databases, testosterone levels were obtained for menages 18-99 from 2010 to 2021 who had at least 2 morning testosterone levels drawn within a 2-year period. All samples were analyzed with liquid chromatography with tandem mass spectrometry. To avoid potential confounding by testosterone-altering medications patients who were currently or previously on exogenous testosterone, endogenous testosterone-stimulating medications, testosterone-suppressing medications, and aromatase inhibitors were excluded from the study.
Results
There were 9495 and 16171 total testosterone levels measured from Miami and Pittsburgh, respectively, with all men having 2 or more levels. There was no statistically significant variation in testosterone levels for the overall cohort in Pittsburgh or Miami, respectively. Additionally, when stratified by age group, no individual groups were found to have significant seasonal variability.
Conclusion
Our findings suggest that although there are differing total testosterone levels between men who reside in 2 different climates, there is no significant variability in testosterone levels between seasons. Therefore, testosterone levels can be checked and interpreted without the need to account for the season during which they were drawn.
Introduction
Awareness of testosterone deficiency and the benefits of initiating hormone replacement for men has increased over the past decade. The prevalence of low testosterone in men over 45 years old is reported to be around 39%.1 It is estimated that nearly 6.5 million men between the ages of 30 and 70 years will have symptomatic testosterone deficiency by the year 2025.2 Low testosterone levels have been shown to be associated with a wide range of issues including erectile dysfunction, cardiovascular comorbidities, diabetes mellitus, osteoporosis, emotional lability, and metabolic syndrome.3 Clinical manifestations of low testosterone may include sleep disturbance, low libido, subfertility, loss of body hair, anemia, reduced strength/physical performance, and increased body fat.4 Testosterone therapy (TT)can correct symptoms associated with testosterone deficiency. Testosterone therapy has the potential to improve libido, erectile function, anemia, increase bone mass density, improved glycemic control, and depressive mood.5,6
For accurate evaluation, clinicians must consider the variations that testosterone undergoes in the human body.7 The diurnal variation of testosterone is well characterized; its levels peak in the morning and decline during the day.8,9 Thus, per American Urological Association guidelines, it is recommended to check morning levels of testosterone for accurate evaluations of testosterone deficiency.10,11 However, there is a lack of consensus on whether there are significant seasonal variations in serum testosterone levels. Several studies have reported possible peaks and troughs across seasons.12-15 Both Dabbs and Lees showed a peak of testosterone levels in winter, while Ballatsella et aland Zornitski et al reported that testosterone peaks in summer. Conversely, other studies concluded that there are no seasonal variations in testosterone.16,17
Our objective was to determine if there is clinically relevant seasonal variability in testosterone levels. We utilized retrospective data of serum testosterone levels in a large cohort of men from 2 different institutions, 1 located in an area with seasons (Pittsburgh, Pa) and 1 without seasons (Miami, Fla). We hypothesized that there would be significant seasonal variability for Pittsburgh, Pa, and that there would be no significant variability for Miami, Fla.
Our study must be interpreted in the context of several limitations. First, we did not assess a variety of potentially significant patient characteristics including ethnicity, body mass index, and medical comorbidities. Second, no information is available about free testosterone, gonadotropins, estradiol, and liver function for our cohort. Thus, we are not able to consider possible seasonal variations of bioavailable testosterone, testosterone-to-estrogen ratio, or the relationship of testosterone with gonadotropins. Third, we did not account for individual exposure to environments outside of their local areas, thus some patients may have had a variable seasonal exposure due to travel. Fourth, there is variability in temperature and daylight hours for the locations that do not have a significant change of seasons (Miami, Fla), which may confound results.
Despite these weaknesses, our study has several strengths. We present findings of seasonal testosterone levels from the largest cohort of men reported thus far, living at 2 separate latitudes, over a long-longitudinal time frame interval, without known testosterone-altering medications, and considered amounts of both daylight and local temperatures. Our findings suggest that although there are differing total testosterone levels between 2 different climates, there is no significant variability in testosterone levels between seasons. Therefore, testosterone levels can be checked and interpreted without the need to account for the season during which they were drawn.
