title: Serum retinol levels and pulmonary function in children and adolescents with cystic fibrosis.
abstract: BACKGROUND
  It has been suggested that higher serum retinol levels could have protective effects on pulmonary function (PF) in patients with cystic fibrosis (CF). However, serum retinol levels will be transiently decreased during pulmonary exacerbation. Therefore, the extent of chronic pulmonary inflammation should be included when describing the association between PF and serum retinol. We assessed the longitudinal relation between serum retinol, immunoglobulin G (IgG) and PF in paediatric CF patients.
  
  
  METHODS
  We studied the serum retinol, IgG and forced expiratory volumes in one second (FEV(1)% pred.) of 228 CF patients during a seven-year follow up period. The cross-sectional and longitudinal relations between these variables were assessed.
  
  
  RESULTS
  Serum retinol, with medians levels between 1.2 and 1.4 μmol/l, were relatively stable, while median serum IgG gradually increased during the age years. The FEV(1)% pred. was longitudinally inversely associated with serum IgG and age, but not with serum retinol. Each g/l increase in serum IgG level was associated with an accelerated yearly decline in FEV(1)% pred. of 0.5% (95% CI -0.8 to -0.1, p=0.008), and each year increase in age was associated with a 1.7% (95% CI -2.1 to -1.3, p=0.000) decline in FEV(1)% pred. This effect was not observed with respect to serum retinol levels (95% CI -1.9 to 2.2, p=0.570).
  
  
  CONCLUSIONS
  In this large sample of children and adolescents with CF, we found no evidence that higher serum retinol levels had protective effects on PF.
authors.affiliation: Internal Medicine and Dermatology, Dietetics, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Cystic Fibrosis Centre Utrecht, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands. Electronic address: j.w.woestenenk@umcutrecht.nl.
authors.forename: J W
authors.initials: JW
authors.lastname: Woestenenk
authors.affiliation: Cystic Fibrosis Centre Utrecht, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Department of Paediatric Pulmonology, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: Broos
authors.affiliation: Department of Biostatistics, Julius Centre, University Medical Centre Utrecht, STR.7.125, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: R K
authors.initials: RK
authors.lastname: Stellato
authors.affiliation: Cystic Fibrosis Centre Utrecht, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Department of Paediatric Pulmonology, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: H G M
authors.initials: HG
authors.lastname: Arets
authors.affiliation: Department of Paediatric Pulmonology, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Cystic Fibrosis Centre Utrecht, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: C K
authors.initials: CK
authors.lastname: van der Ent
authors.affiliation: Department of Paediatric Gastroenterology, University Medical Centre Utrecht, KE.04.133.1, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Cystic Fibrosis Centre Utrecht, University Medical Centre Utrecht, KH.01.419.0, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: R H J
authors.initials: RH
authors.lastname: Houwen
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D002648:Child; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000097:blood* / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D014801:Vitamin A / Q000097:blood*
chemical_list: D015415:Biomarkers; D014801:Vitamin A
keywords: Cystic fibrosis; Immunoglobulin G; Respiratory function; Retinol