Prevalence of 25-hydroxyvitamin D deficiency in Korean adolescents: association with age, season and parental vitamin D status

ObjectiveWe aimed to assess the prevalence and associated factors of vitamin D deficiency in healthy adolescents and to determine parent-adolescent association in vitamin D status.DesignA cross-sectional study.SettingData from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using I-125-labelled RIA kits. Vitamin D deficiency in adolescents was defined as 25(OH)D level <275 nmol/l, and 25(OH)D levels between 275 and <50 nmol/l were considered insufficient. For the parents, vitamin D deficiency was defined as 25(OH)D level <50 nmol/l.SubjectsThe study population consisted of 2062 adolescents (1095 boys, 967 girls; aged 10-18 years) and their parents (1005 fathers, 1341 mothers).ResultsOverall, 134 % of adolescents (boys 117 %, girls 154 %) were 25(OH)D deficient, 547 % were 25(OH)D insufficient. Prevalence of vitamin D deficiency increased with age (P < 00001). Parental vitamin D deficiency was more prevalent in vitamin D-deficient adolescents than in non-deficient adolescents (all P < 00001). In multivariate logistic regression analyses, predictors for vitamin D deficiency were senior high school students (OR = 345-433), winter/spring season (OR = 318-511/535-736) and parental vitamin D deficiency (OR = 178-488; all P < 005).ConclusionsVitamin D insufficiency is prevalent among healthy Korean adolescents and the parent-offspring association warrants vitamin D screening for family members of deficient individuals.