title: Cystic fibrosis-related bone disease explored using a four step algorithm.
abstract: BACKGROUND
  A suboptimal bone accrual in young individuals with cystic fibrosis (CF) may be related to the development of a premature CF-related bone disease. Dual energy X-ray absorptiometry (DXA) is the mainstream measure of bone health; however, the influence of body size and lean tissue mass (LTM) on bone data is poorly interpreted.
  
  
  METHODS
  Total body dual-energy X-ray absorptiometry (DXA) measurements of bone mineral content (BMC) and LTM in 53 individuals with CF (7.00-17.99years) were compared to 53 sex-matched controls. BMC, height, and LTM in relation to height and BMC Z-scores were calculated and used in a 4-step algorithm.
  
  
  RESULTS
  Pubertal females with CF had less total body BMC for age (p=0.02); pre-pubertal males (p=0.05) and pubertal females with CF (p=0.03) were shorter; and pubertal females with CF showed less total body BMC for LTM (p=0.01).
  
  
  CONCLUSIONS
  The algorithm showed the following: (1) prior to puberty lowered total body BMC was primarily due to short stature, (2) LTM was appropriate for body size, and (3) pubertal females with CF had significantly less total body BMC for their LTM. Longer controlled trials are needed to clinically interpret CF-related bone disease using DXA derived data that considers patient size and body composition.
authors.affiliation: The University of Queensland, Children's Nutrition Research Centre, Queensland Children's Medical Research Institute, Brisbane, Australia; The University of Queensland, Children's Nutrition Research Centre, School of Medicine, Brisbane, Australia. Electronic address: d.brookes@uq.edu.au.
authors.forename: Denise S K
authors.initials: DS
authors.lastname: Brookes
authors.affiliation: The Children's Hospital at Westmead, Sydney, Australia.
authors.forename: Julie N
authors.initials: JN
authors.lastname: Briody
authors.affiliation: The Children's Hospital at Westmead, Sydney, Australia; University of Sydney, School of Medicine, Australia.
authors.forename: Craig F
authors.initials: CF
authors.lastname: Munns
authors.affiliation: The University of Queensland, Children's Nutrition Research Centre, Queensland Children's Medical Research Institute, Brisbane, Australia; The University of Queensland, Children's Nutrition Research Centre, School of Medicine, Brisbane, Australia.
authors.forename: Peter S W
authors.initials: PS
authors.lastname: Davies
authors.affiliation: The University of Queensland, Children's Nutrition Research Centre, Queensland Children's Medical Research Institute, Brisbane, Australia; The University of Queensland, Children's Nutrition Research Centre, School of Medicine, Brisbane, Australia.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Hill
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D000465:Algorithms; D001823:Body Composition; D001827:Body Height; D018488:Bone Demineralization, Pathologic / Q000175:diagnosis / Q000453:epidemiology*; D015519:Bone Density / Q000502:physiology*; D001847:Bone Diseases / Q000175:diagnosis / Q000453:epidemiology; D002648:Child; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011379:Prognosis; D011793:Queensland; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index
keywords: Algorithm; BMC; Cystic fibrosis; DXA; Height; LTM