Vitamin D levels and deficiency according to seasons
Mean vitamin D levels were 23.6±17.3 ng/mL for autumn, 23.3±18.0ng/ml for summer, 19.6±18.5 ng/ml for winter and 20.0±18.6 ng/ml for spring.
Median vitamin D levels were higher in autumn and summer serum samples compared to winter and spring serum samples (p<0.001) (Table 1). The frequency of vitamin D deficiency was higher in January, February, March, and April compared to in June, July, August, September, and October (p=0.005) (Figure 1). While the frequency of vitamin D deficiency was the highest in February (71.6%) it was the lowest in September with a 44.2% ratio.