Fig 1.
Frequency distribution of the serum 25(OH)D concentration in 5,571 young children.
The serum 25(OH)D level ranged from 20.6–132.9 nmol/L with a median value of 71.5 nmol/L and most values of 25(OH)D levels were more than 50 nmol/L.
Fig 2.
Proportion of different categories of the serum 25(OH)D level in the study population.
Serum 25(OH)D levels were sectioned into four categories indicated by different color (<30 nmol/L, 30–49.9 nmol/L, 50–74.9 nmol/L and ≥75 nmol/L). n indicated children number in each category.
Fig 3.
Comparison of the serum 25(OH)D concentration among young children in different seasons.
The serum 25(OH)D level was highest in summer and lowest in autumn.
Fig 4.
Comparison of the serum 25(OH)D concentration among young children at different ages.
As the children grew older, the median serum 25(OH)D level was decreased.
Table 1.
Comparison of serum 25(OH)D levels in 5,571 young children stratified by age, season or gender.
Table 2.
Categories of vitamin D status by age, season or gender (n = 5,571).
Fig 5.
Comparison of the prevalence of vitamin D deficiency in young children by age and season.
Vitamin D deficiency was defined as a serum 25(OH)D level of <50 nmol/L. All the children were stratified by age into three subgroups (aged 1, 2 and 3). In each subgroup, the subjects were further stratified by season of serum collection. The prevalence of vitamin D deficiency in each season was calculated separately within each age group.