Comparison of serum 25(OH)D levels in 5,571 young children stratified by age, season or gender.

Values of serum 25(OH)D levels were compared using Mann–Whitney U test.a significant difference between children aged 1y and aged 2y (Pb Significant difference between children aged 1y and aged 3y (Pc Significant difference between children aged 2y and aged 3y (Pd No significant difference between spring and summer (P = 0.076).e Significant difference between spring and autumn (Pf No significant difference between spring and winter (P = 0.098).g Significant difference between summer and autumn (Ph Significant difference between summer and winter (P = 0.001).i Significant difference between autumn and winter (P = 0.003).j No significant difference between boys and girls (P = 0.121).Comparison of serum 25(OH)D levels in 5,571 young children stratified by age, season or gender.