title: A retrospective analysis of longitudinal changes in bone mineral content in cystic fibrosis.
abstract: BACKGROUND
  We aimed to describe the longitudinal changes in bone mineral content and influencing factors, in children with cystic fibrosis (CF).
  
  
  METHODS
  One hundred children (50 females) had dual X-ray absorptiometry (DXA) performed. Of these, 48 and 24 children had two to three scans, respectively over 10 years of follow-up. DXA data were expressed as lumbar spine bone mineral content standard deviation score (LSBMCSDS) adjusted for age, gender, ethnicity and bone area. Markers of disease, anthropometry and bone biochemistry were collected retrospectively.
  
  
  RESULTS
  Baseline LSBMCSDS was >0.5 SDS in 13% children, between -0.5; 0.5 SDS, in 50% and ≤-0.5 in the remainder. Seventy-eight percent of the children who had baseline LSBMCSDS >-0.5, and 35% of the children with poor baseline (LSBMCSDS<-0.5), showed decreasing values in subsequent assessments. However, mean LS BMC SDS did not show a significant decline in subsequent assessments (-0.51; -0.64; -0.56; p=0.178). Lower forced expiratory volume in 1 s percent (FEV1%) low body mass index standard deviation scores (BMI SDS) and vitamin D were associated with reduction in BMC.
  
  
  CONCLUSIONS
  Bone mineral content as assessed by DXA is sub-optimal and decreases with time in most children with CF and this study has highlighted parameters that can be addressed to improve bone health.
authors.affiliation: .
authors.forename: Adela
authors.initials: A
authors.lastname: Chirita-Emandi
authors.affiliation: .
authors.forename: Sheila
authors.initials: S
authors.lastname: Shepherd
authors.affiliation: .
authors.forename: Andreas
authors.initials: A
authors.lastname: Kyriakou
authors.affiliation: .
authors.forename: Jane D
authors.initials: JD
authors.lastname: McNeilly
authors.affiliation: .
authors.forename: Carol
authors.initials: C
authors.lastname: Dryden
authors.affiliation: .
authors.forename: Donna
authors.initials: D
authors.lastname: Corrigan
authors.affiliation: .
authors.forename: Anne
authors.initials: A
authors.lastname: Devenny
authors.affiliation: .
authors.forename: Syed Faisal
authors.initials: SF
authors.lastname: Ahmed
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D015519:Bone Density / Q000502:physiology*; D002648:Child; D003550:Cystic Fibrosis / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D008297:Male; D012189:Retrospective Studies; D014916:Whole-Body Irradiation / Q000379:methods
keywords: bone mineral content; children; cystic fibrosis; dual-energy X-ray absorptiometry (DXA); longitudinal study; markers of disease