Seasonal Variation of Testosterone Levels in a Large Cohort of Men

Table 3

Total and bioavailable testosterone levels determined in different months.

	N	Mean	Median	value
Total testosterone, nmol/L
March	2334	14.7 ± 5.5	13.8
August	2130	15.7 ± 5.9	14.9	<0.001
September	1761	15.7 ± 5.9	15.1	<0.001
October	2093	15.4 ± 5.8	14.7	<0.001
Bioavailable testosterone, nmol/L
March	734	6.7 ± 2.5	6.2
August	660	7.2 ± 2.8	6.7	<0.001
September	486	7.0 ± 2.8	6.6	<0.001
October	589	7.3 ± 3.0	6.8	<0.001

Values are expressed as mean ± SD. value is derived in comparison with levels in March.