title: Intestinal current measurement versus nasal potential difference measurements for diagnosis of cystic fibrosis: a case-control study.
abstract: BACKGROUND
  Nasal potential difference (NPD) and intestinal current measurement (ICM) are functional CFTR tests that are used as adjunctive diagnostic tools for cystic fibrosis (CF). Smoking has a systemic negative impact on CFTR function. A diagnostic comparison between NPD and ICM and the impact of smoking on both CFTR tests has not been done.
  
  
  METHODS
  The sweat chloride test, NPD, and ICM were performed in 18 patients with CF (sweat chloride >60 mmol/l), including 6 pancreatic sufficient (PS) patients, and 13 healthy controls, including 8 smokers. The NPD CFTR response to Cl-free and isoproterenol perfusion (Δ0Cl- + Iso) was compared to the ICM CFTR response to forskolin/IBMX, carbachol, and histamine (ΔIsc, forskolin/IBMX+ carbachol+histamine).
  
  
  RESULTS
  The mean NPD CFTR response and ICM CFTR response between patients with CF and healthy controls was significantly different (p <0.001), but not between patients with CF who were PS and those who were pancreatic insufficient (PI). Smokers have a decreased CFTR response measured by NPD (p = 0.049). For ICM there is a trend towards decreased CFTR response (NS). Three healthy control smokers had NPD responses within the CF-range. In contrast to NPD, there was no overlap of the ICM response between patients with CF and controls.
  
  
  CONCLUSIONS
  ICM is superior to NPD in distinguishing between patients with CF who have a sweat chloride > 60 mmol/l and healthy controls, including smokers. Neither NPD nor ICM differentiated between patients with CF who were PS from those who were PI. Smoking has a negative impact on CFTR function in healthy controls measured by NPD and challenges the diagnostic interpretation of NPD, but not ICM.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Bagheri-Hanson
authors.forename: Sebastian
authors.initials: S
authors.lastname: Nedwed
authors.forename: Claudia
authors.initials: C
authors.lastname: Rueckes-Nilges
authors.affiliation: Department of Pediatrics, Justus-Liebig-University Giessen, Feulgenstrasse 12, 35385 Giessen, Germany. lutz.naehrlich@paediat.med.uni-giessen.de.
authors.forename: Lutz
authors.initials: L
authors.lastname: Naehrlich
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002648:Child; D002712:Chlorides / Q000032:analysis / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000503:physiopathology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000503:physiopathology*; D008297:Male; D009666:Nose; D012007:Rectum; D020545:Respiratory Mucosa / Q000503:physiopathology*; D012907:Smoking / Q000503:physiopathology*; D013542:Sweat / Q000737:chemistry; D055815:Young Adult
chemical_list: C505032:CFTR protein, human; D002712:Chlorides; D019005:Cystic Fibrosis Transmembrane Conductance Regulator