title: Relationship between sweat chloride, sodium, and age in clinically obtained samples.
abstract: BACKGROUND
  The relationship between sweat electrolytes and age is uncertain, as is the value of measuring sodium or the chloride:sodium ratio.
  
  
  METHODS
  13,785 sweat tests performed over 23 years at one center through the Macroduct collection in clinically obtained samples were analyzed.
  
  
  RESULTS
  Sweat chloride tended to decrease over the first year of life, slowly increase until the fourth decade, then either level off or slightly decrease. In children, sweat sodium overlapped between those with positive and negative sweat tests, but not in adults. If the sweat test was positive, there was a higher likelihood of having a chloride:sodium ratio >1, but most subjects with a ratio >1 did not have CF.
  
  
  CONCLUSIONS
  Sweat chloride and sodium vary with age. Measurement of sweat sodium did not add discriminatory value. The proportion of subjects with a chloride:sodium ratio >1, with or without CF, varied greatly between age ranges.
authors.affiliation: New York Medical College, Department of Pediatrics, Division of Pediatric Pulmonology, Allergy, and Sleep Medicine Munger Pavilion Room 106, Valhalla, NY 10595, United States; The Armond V. Mascia, MD Cystic Fibrosis Center of the Maria Fareri Children's Hospital at Westchester Medical Center, Valhalla, NY, United States. Electronic address: nadav_traeger@nymc.edu.
authors.forename: Nadav
authors.initials: N
authors.lastname: Traeger
authors.affiliation: New York Medical College, Department of Epidemiology and Community Health, School of Health Sciences and Practice, Valhalla, NY 10595, United States.
authors.forename: Qiuhu
authors.initials: Q
authors.lastname: Shi
authors.affiliation: New York Medical College, Department of Pediatrics, Division of Pediatric Pulmonology, Allergy, and Sleep Medicine Munger Pavilion Room 106, Valhalla, NY 10595, United States; The Armond V. Mascia, MD Cystic Fibrosis Center of the Maria Fareri Children's Hospital at Westchester Medical Center, Valhalla, NY, United States.
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Dozor
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002624:Chemistry, Clinical / Q000379:methods / Q000592:standards; D002648:Child; D002675:Child, Preschool; D002712:Chlorides / Q000032:analysis / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015997:Neonatal Screening / Q000379:methods / Q000592:standards; D012016:Reference Values; D012189:Retrospective Studies; D012964:Sodium / Q000032:analysis / Q000378:metabolism*; D013542:Sweat / Q000737:chemistry / Q000378:metabolism*; D055815:Young Adult
chemical_list: D002712:Chlorides; D012964:Sodium
keywords: Cystic fibrosis; Electrolytes; Newborn screening; Sweat