Table 2. Seasonal variation in average total testosterone and 25(OH)D levels after adjustment for confounding variables.

Calculated by analysis of covariance. Model 1: no adjustment; model 2: adjusted for age; model 3: adjusted for age, total cholesterol, and physical activity; model 4: adjusted for age, total cholesterol, low-density lipoprotein, high-density lipoprotein, waist circumference, body mass index, fasting glucose, physical activity, alcohol use, and smoking.

25(OH)D, 25-hydroxyvitamin D.