title: Cystic fibrosis with normal sweat chloride concentration--case report.
abstract: Cystic fibrosis is a genetic disease usually diagnosed by abnormal sweat testing. We report a case of an 18-year-old female with bronchiectasis, chronic P. aeruginosa infection, and normal sweat chloride concentrations who experienced rapid decrease of lung function and clinical deterioration despite treatment. Given the high suspicion of cystic fibrosis, broad genotyping testing was performed, showing a compound heterozygous with deltaF508 and 3849+10 kb C-->T mutations, therefore confirming cystic fibrosis diagnosis. Although the sweat chloride test remains the gold standard for the diagnosis of cystic fibrosis, alternative diagnostic tests such as genotyping and electrophysiologic measurements must be performed if there is suspicion of cystic fibrosis, despite normal or borderline sweat chloride levels.
authors.affiliation: Children's Institute, Hospital das Clínicas, Faculty of Medicine, University of São Paulo, São Paulo/SP, Brazil.
authors.forename: Luiz Vicente Ferreira da
authors.initials: LV
authors.lastname: Silva Filho
authors.forename: Maria Helena de Carvalho Ferreira
authors.initials: MH
authors.lastname: Bussamra
authors.forename: Cleyde Miriam Aversa
authors.initials: CM
authors.lastname: Nakaie
authors.forename: Fabíola Villac
authors.initials: FV
authors.lastname: Adde
authors.forename: Joaquim Carlos
authors.initials: JC
authors.lastname: Rodrigues
authors.forename: Salmo
authors.initials: S
authors.lastname: Raskin
authors.forename: Tatiana
authors.initials: T
authors.lastname: Rozov
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000032:analysis; D002712:Chlorides / Q000032:analysis*; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D009154:Mutation; D013542:Sweat / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D002712:Chlorides