Seasonal Variation of Testosterone Levels in a Large Cohort of Men

Table 4

Linear regression analysis of variables associated with total testosterone (A) and bioavailable testosterone (B).

Variable	β	95% CI	value
(A)
Test performed in March vs. August-October	−0.784	−1.046 to −0.523	<0.001
Age (per year)	−0.028	−0.037 to −0.019	<0.001
BMI (per unit)	−0.395	−0.420 to −0.370	<0.001
Current smoking	0.765	0.483 to 1.046	<0.001
Past smoking	0.105	−0.246 to 0.456	0.558
Diabetes	−0.800	−1.170 to −0.431	<0.001
(B)
Test performed in March vs. August–October	−0.593	−1.058 to −0.128	0.013
Age (per year)	−0.029	−0.045 to −0.012	0.001
BMI (per unit)	−0.440	−0.486 to −0.394	<0.001
Current smoking	0.733	0.216 to 1.250	0.005
Past smoking	−0.096	−0.729 to 0.536	0.766
Diabetes	−0.803	−1.461 to −0.145	0.017