title: Diagnosis of cystic fibrosis by sweat testing: age-specific reference intervals.
abstract: OBJECTIVE
  To develop reference intervals (RIs) for sweat chloride and sodium in healthy children, adolescents, and adults.
  
  
  METHODS
  Healthy, unrelated subjects aged from 5 to >50 years and subjects who were pancreatic insufficient with cystic fibrosis (CF) were recruited. Sweat collection was performed on all subjects with the Wescor Macroduct system. Sweat electrolytes were analyzed with direct ion selective electrodes. DeltaF508 mutation analysis was performed on the healthy subjects >/=15 years old.
  
  
  RESULTS
  A total of 282 healthy and 40 subjects with CF were included for analysis. There was no overlap of sweat chloride between the group with CF and the group without CF, but there was some overlap of sweat sodium. Sweat chloride increased with age, with the rate of increase slowing progressively to zero after the age of 19 years. The estimated median (95% RI) for sweat chloride were: 5 to 9 years, 13 mmol/L (1-39 mmol/L); 10 to 14 years, 18mmol/L (3-47 mmol/L); 15 to 19 years, 20 mmol/L (3-51mmol/L); and 20+ years 23 mmol/L (5-56mmol/L).
  
  
  CONCLUSIONS
  We have successfully developed the age-related RI for sweat electrolytes, which will be useful for clinicians interpreting sweat test results from children, adolescents, and adults.
authors.affiliation: Department of Biochemical Genetics, VCGS Pathology, The Royal Children's Hospital, Parkville, Victoria, Australia.
authors.forename: Avantika
authors.initials: A
authors.lastname: Mishra
authors.forename: Ronda
authors.initials: R
authors.lastname: Greaves
authors.forename: Katherine
authors.initials: K
authors.lastname: Smith
authors.forename: John B
authors.initials: JB
authors.lastname: Carlin
authors.forename: Andrew
authors.initials: A
authors.lastname: Wootton
authors.forename: Rob
authors.initials: R
authors.lastname: Stirling
authors.forename: John
authors.initials: J
authors.lastname: Massie
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D002712:Chlorides / Q000378:metabolism*; D015331:Cohort Studies; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012016:Reference Values; D012964:Sodium / Q000378:metabolism*; D013542:Sweat / Q000737:chemistry*; D055815:Young Adult
chemical_list: D002712:Chlorides; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D012964:Sodium