title: Nasal potential difference in non-classic cystic fibrosis-long term follow up.
abstract: BACKGROUND
  Nasal potential difference (NPD) measurement is an electrophysiological test that assesses cystic fibrosis transmembrane conductance regulator (CFTR) activity and is a recognized diagnostic tool in CF. The aim of this study is to assess in the long term the role of NPD in patients whose diagnosis is questionable.
  
  
  METHODS
  We performed follow up study on 70 patients with questionable CF (QCF) who were divided previously into two groups according to their NPD results: patients who likely have CF (QCF-CF) (n = 24), and those who likely do not have CF (QCF-non-CF) (n = 46).
  
  
  RESULTS
  Sixty out of 70 patients were available for study. Sixteen patients in the QCF-CF group were being followed up at CF Centers as opposed to 1 in the QCF-non-CF group (P < 0.01). Seven patients from the QCF-CF group developed sinusitis during the follow up years compared to none from the QCF-non-CF group. During the years of the follow up, 17 QCF-non-CF patients were diagnosed with other medical conditions that could explain their previous symptoms. On repeated NPD measurement in the QCF-CF group, the results were similar to the original test.
  
  
  CONCLUSIONS
  This study supports the diagnostic role of NPD measurement. Larger cohort studies are required for confirmation.
authors.affiliation: Cystic Fibrosis Center, Hadassah University Hospital, Jerusalem, Israel.
authors.forename: Ranit
authors.initials: R
authors.lastname: Jaron
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Yaakov
authors.forename: Joseph
authors.initials: J
authors.lastname: Rivlin
authors.forename: Hannah
authors.initials: H
authors.lastname: Blau
authors.forename: Lea
authors.initials: L
authors.lastname: Bentur
authors.forename: Yakov
authors.initials: Y
authors.lastname: Yahav
authors.forename: Eitan
authors.initials: E
authors.lastname: Kerem
authors.forename: Haim
authors.initials: H
authors.lastname: Bibi
authors.forename: Elie
authors.initials: E
authors.lastname: Picard
authors.forename: Michael
authors.initials: M
authors.lastname: Wilschanski
mesh_terms: D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000503:physiopathology*; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D008564:Membrane Potentials; D009297:Nasal Mucosa / Q000503:physiopathology*; D015203:Reproducibility of Results