title: Prevalence of 25-hydroxyvitamin D deficiency in Korean adolescents: association with age, season and parental vitamin D status.
abstract: OBJECTIVE
  We 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.
  
  
  METHODS
  A cross-sectional study.
  
  
  METHODS
  Data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using 125I-labelled RIA kits. Vitamin D deficiency in adolescents was defined as 25(OH)D level <27·5 nmol/l, and 25(OH)D levels between 27·5 and <50 nmol/l were considered insufficient. For the parents, vitamin D deficiency was defined as 25(OH)D level <50 nmol/l.
  
  
  METHODS
  The study population consisted of 2062 adolescents (1095 boys, 967 girls; aged 10-18 years) and their parents (1005 fathers, 1341 mothers).
  
  
  RESULTS
  Overall, 13·4% of adolescents (boys 11·7%, girls 15·4%) were 25(OH)D deficient, 54·7% were 25(OH)D insufficient. Prevalence of vitamin D deficiency increased with age (P < 0·0001). Parental vitamin D deficiency was more prevalent in vitamin D-deficient adolescents than in non-deficient adolescents (all P < 0·0001). In multivariate logistic regression analyses, predictors for vitamin D deficiency were senior high school students (OR = 3·45-4·33), winter/spring season (OR = 3·18-5·11/5·35-7·36) and parental vitamin D deficiency (OR = 1·78-4·88; all P < 0·05).
  
  
  CONCLUSIONS
  Vitamin D insufficiency is prevalent among healthy Korean adolescents and the parent-offspring association warrants vitamin D screening for family members of deficient individuals.
authors.affiliation: 1 Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, 761-1 Sanggye-7-dong, Nowon-gu, Seoul 139-707, Republic of Korea.
authors.forename: Shin Hye
authors.initials: SH
authors.lastname: Kim
authors.affiliation: 2 Clinical Trial Center, Busan Paik Hospital, Inje University College of Medicine, Busan, Republic of Korea.
authors.forename: Min Kyung
authors.initials: MK
authors.lastname: Oh
authors.affiliation: 3 Department of Pediatrics, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemung-gu, Seoul 120-752, Republic of Korea.
authors.forename: Ran
authors.initials: R
authors.lastname: Namgung
authors.affiliation: 1 Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, 761-1 Sanggye-7-dong, Nowon-gu, Seoul 139-707, Republic of Korea.
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Park
mesh_terms: D000293:Adolescent; D044466:Asian People; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D009749:Nutrition Surveys; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D012621:Seasons; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D014807:Vitamin D