Seasonal Variation of Testosterone and Waist to Hip Ratio in Men: The Tromsø Study

[David PS]

It looks like the month that you test your testosterone levels will have a large impact on the results. Steroid analysis [hair or (toe)nail] would average the variation over weeks or months.

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Seasonal Variation of Testosterone and Waist to Hip Ratio in Men: The Tromsø Study

Studies of seasonal variation in male testosterone levels show contradictory results. We report here a cross-sectional study of the seasonal variation in total

academic.oup.com

Studies of seasonal variation in male testosterone levels show contradictory results. We report here a cross-sectional study of the seasonal variation in total and free testosterone, LH, and SHBG levels in 1548 men living in north Norway, a population exposed to a wide seasonal variation in temperature and daylight. Total testosterone showed a bimodal seasonal variation (P < 0.001) with a small peak in February, the nadir in June, and a more prominent peak in October and November. Free testosterone also showed a significant seasonal pattern (P < 0.001), with the peak in December and the nadir in August. These patterns persisted after adjusting for age and waist to hip ratio (P < 0.001).

Lowest testosterone levels occurred in months with the highest temperatures and longest hours of daylight. Waist to hip ratio paralleled the change in daylight and temperature, with the highest values during the summer and was thus inversely related to the seasonal testosterone variation.

The variations in hormone levels were large, with a 31% difference between the lowest and highest monthly mean level of free testosterone. Prospective studies are needed to establish the direction of the association and its etiology.

https://academic.oup.com/view-large/figure/53346857/eg0739609001.jpeg

 

[David PS]

Here is another study from 2009.

Sci-Hub | Age and Seasonal Variation in Serum Testosterone Concentration Among Men. Chronobiology International, 7(3), 245–249 | 10.3109/07420529009056982

Abstract-Serum testosterone concentrations from 4,462 military veterans, ages 32-44, were examined for age andseasonal variation. Testosterone concentrations were assayed from a single serum sample from each subject. Allsamples were drawn before breakfast, at about 8:OO a.m., from subjects recruited over a 16-month study period.Mean levels declined with age (P < .001), from 864 ng/dl at age 32 to 602 ng/dl at age 44. Mean levels also variedwith month of testing (P < .Ol), with a seasonal peak in December (the seasonal peak was in November for men intheir early 30s). The age effect was greater than the seasonal effect. Both effects may bear upon behaviour and should be treated as possible sources of error in studies of testosterone.

 

[Androsclerosis]

How it would be possible that during the summer testosterone is at its lowest point.

 

[Androsclerosis]

This study makes no sense. Why would you pick Norwegians from the north for the test? It seems like this study was made to give the impression that the sun is unhealthy.

 

[David PS]

How it would be possible that during the summer testosterone is at its lowest point.

I am just trying to cover the studies.

Sci-Hub | The evidence for seasonal variations of testosterone in men. Maturitas, 74(3), 208–212 | 10.1016/j.maturitas.2012.12.003

Ample evidence exists to support the concept of diurnal variations in testosterone levels; however, substantiation for seasonal fluctuations is sparse and inconsistent. Since circadian disparities exist, laboratory screening for hypogonadism has traditionally been conducted using serum testosterone levels obtained in the early morning. Should circannual variability of testosterone be confirmed, it would make the monitoring of testosterone levels more difficult while forcing the development of seasonal reference standards to allow for comparison. Moreover, decisions to begin treatment and adjustment of practice patterns would likely follow. This review thoroughly explores all of the available evidence concerning seasonal variations in testosterone levels. The impacts of melatonin, vitamin D, sleep–wake cycles, light exposure, physical activity, BMI, and waist circumference are also discussed. Current research suggests that while some evidence exists to support the notion of seasonal testosterone variations, the discussed inconsistencies preclude the incorporation of this concept into current clinical standards.

 

[Mauritio]

That is indeed weird. UV light increases Testosterone, androsterone and Vitamin D.

 

[David PS]

That is indeed weird. UV light increases Testosterone, androsterone and Vitamin D.

Yes, it is weird. I know that it takes months to increase vitamin D. I do not know how many months it takes to naturally ramp up testosterone and androsterone.

I am wondering if humans have a biological basis for the distribution of birth rates from month to month. For animals, it is called a mating season.

Has nature evolved so that conceptions occurs most favorably in the months that are most likely to ensure the survivability of both the baby and the mother?

see also