ABSTRACT
BACKGROUND: The objective of this study was to assess the serum 25-hydroxyvitamin D (25OHD) status and evaluate the associated factors in a Korean pediatric population aged 0-18 yr. METHODS: Serum 25OHD levels were retrospectively analyzed in 13,236 Korean children and adolescents. 25OHD tests by chemiluminescent immunoassay were requested from 332 medical institutions nationwide in Korea between January 2014 and December 2014. Prevalence of vitamin D deficiency (VDD) and insufficiency (VDI) and the associated factors were analyzed. VDD and VDI were defined as serum 25OHD levels of <20.0 ng/mL and 20.0-29.9 ng/mL, respectively. RESULTS: The 25OHD levels negatively correlated with age (r=-0.4033, P<0.001). Overall, 79.8% boys and 83.8% girls had hypovitaminosis D (VDI or VDD). The Odds ratios (ORs) of being in the VDD/VDI category as against the reference category of VDS (vitamin D sufficiency) were as follows: increase in age by 1 yr (OR=1.42/1.25, all P<0.001); girls (OR=1.32/1.16, P<0.001/P=0.004) compared to boys, spring (OR=1.61/1.80), fall (OR=1.31/1.28), and winter (OR=1.44/2.03, all P<0.001) compared to summer season; living in urban areas (OR=1.23, P<0.001) compared to rural areas. CONCLUSIONS: VDD and VDI are highly prevalent in children and adolescents in Korea. Serum 25OHD levels decreased significantly according to increasing age. Winter and spring seasons, increasing age, female sex, and living in urban areas are the factors associated with a high risk of VDD or VDI.