title: Prevalence of inadequate vitamin d status and associated factors in children with cystic fibrosis.
abstract: BACKGROUND
  This study aimed to determine the prevalence of inadequate serum 25-hydroxyvitamin D (25(OH)D) levels in a pediatric Canadian cystic fibrosis (CF) population and to assess the effectiveness of a vitamin D supplementation protocol on improving vitamin D status. A secondary objective was to analyze factors that may be associated with inadequate 25(OH)D levels.
  
  
  METHODS
  Vitamin D supplementation, 25(OH)D levels, and factors hypothesized to be associated with 25(OH)D levels were collected through a retrospective chart review (2010 and 2011) of 96 patients (1-18 years) at one CF clinic in Canada. Adequacy of 25(OH)D was set at ≥75 nmol/L. Patients with inadequate 25(OH)D levels in 2010 were prescribed an additional 1000 IU/d for levels <60 nmol/L or 400 IU/d for levels 60-75 nmol/L.
  
  
  RESULTS
  Inadequate 25(OH)D levels were observed in 26% of patients in 2010 and 23% in 2011. After supplementation was increased for those with inadequate 25(OH)D levels in 2010 (n = 20), a significant increase in 25(OH)D levels was observed in 2011 (P = .03). Adequate status was achieved in 50% of these patients (n = 10). Age was significantly negatively associated with 25(OH)D levels in both years (P = .002). Percentage of forced expiratory volume in 1 second was significantly positively associated with 25(OH)D levels in 2011 (P = .03).
  
  
  CONCLUSIONS
  While vitamin D supplementation was effective at increasing serum 25(OH)D, this protocol did not achieve optimal serum 25(OH)D levels in 25% of the population. Increasing age had the strongest association with 25(OH)D. Current supplementation protocols may require reevaluation based on emerging evidence and revised Cystic Fibrosis Foundation guidelines.
authors.affiliation: Faculty of Agriculture, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Norton
authors.affiliation: Faculty of Agriculture, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Page
authors.affiliation: Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Melissa
authors.initials: M
authors.lastname: Sheehan
authors.affiliation: Faculty of Agriculture, Life and Environmental Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Vera
authors.initials: V
authors.lastname: Mazurak
authors.affiliation: Alberta Health Services, Edmonton, Alberta, Canada.
authors.forename: Kim
authors.initials: K
authors.lastname: Brunet-Wood
authors.affiliation: Alberta Health Services, Edmonton, Alberta, Canada bodil.larsen@albertahealthservices.ca.
authors.forename: Bodil
authors.initials: B
authors.lastname: Larsen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002170:Canada; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000097:blood*; D019587:Dietary Supplements; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000178:diet therapy* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: cystic fibrosis; pediatrics; vitamin D; vitamin D deficiency