title: Risk factors for low serum 25-hydroxyvitamin D concentrations in otherwise healthy children and adolescents.
abstract: BACKGROUND
  Serum 25-hydroxyvitamin D [25(OH)D] concentrations serve as a biomarker for vitamin D stores. Prior studies have not examined the risk factors for low vitamin D concentrations in a multiethnic sample of US youth across a broad age range.
  
  
  OBJECTIVE
  The objective was to determine the prevalence of and factors associated with low concentrations of 25(OH)D in children and adolescents.
  
  
  METHODS
  Serum 25(OH)D concentrations were measured in 382 healthy children aged 6-21 y living in the northeastern United States. Dietary and supplemental vitamin D intake was assessed by interview. Fat and lean mass were assessed by dual-energy X-ray absorptiometry. Multivariable ordinal logistic regression was used to determine factors associated with decreased concentrations of 25(OH)D.
  
  
  RESULTS
  The median concentration of 25(OH)D was 28 ng/mL (interquartile range: 19-35 ng/mL), and 55% of subjects had 25(OH)D concentrations <30 ng/mL. 25(OH)D concentrations were inversely correlated with parathyroid hormone concentrations (Spearman's r=-0.31, P<0.001) but were not significantly correlated with 1,25-dihydroxyvitamin D concentrations. In the multivariable model, older age (P<0.001), black race [odds ratio (OR): 14.2; 95% CI: 8.53, 23.5], wintertime study visit (OR: 3.55; 95% CI: 2.29, 5.50), and total daily vitamin D intake <200 IU (OR: 1.58; 95% CI: 1.02, 2.46) were associated with low vitamin D concentrations. Fat and lean mass were not independently associated with vitamin D status in this healthy-weight sample.
  
  
  CONCLUSIONS
  Low serum 25(OH)D concentrations are prevalent in otherwise healthy children and adolescents in the northeastern United States and are related to low vitamin D intake, race, and season.
authors.affiliation: Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors.forename: Francis L
authors.initials: FL
authors.lastname: Weng
authors.forename: Justine
authors.initials: J
authors.lastname: Shults
authors.forename: Mary B
authors.initials: MB
authors.lastname: Leonard
authors.forename: Virginia A
authors.initials: VA
authors.lastname: Stallings
authors.forename: Babette S
authors.initials: BS
authors.lastname: Zemel
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D001823:Body Composition; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D010281:Parathyroid Hormone / Q000097:blood; D012307:Risk Factors; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: C470125:PTH protein, human; D010281:Parathyroid Hormone; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase