The Need for Vigilance: The Case of a False-Negati... [Pediatrics. 2011] - PubMed result

The Need for Vigilance: The Case of a False-Negati...[Pediatrics.2011] - PubMed result: "Pediatrics.2011 Jul 4.[Epub ahead of print]Department of Pediatrics, University of Minnesota and University of Minnesota Amplatz Children's Hospital, Minneapolis, Minnesota; and.Cystic fibrosis (CF) is the most common life-limiting recessive genetic disorder in the white population.CF is caused by abnormalities in the gene that codes for the cystic fibrosis transmembrane conductance regulator protein (CFTR) and may result in severe chronic lung disease, poor growth, and malnutrition.Physicians often do not consider CF in the differential diagnosis of an infant with failure to thrive in the presence of a negative newborn screening (NBS) result.In Minnesota, newborn infants are screened for CF by immunoreactive trypsinogen (IRT) testing followed by DNA analysis if the IRT screen result is abnormal.All positive NBS results are followed by confirmatory sweat-testing by pilocarpine iontophoresis.We present here the case of a 1-month-old white boy with failure to thrive, chronic diarrhea, and severe malnutrition.Minnesota state CF NBS results were negative at birth (IRT: 43 ng/mL [96% cutoff value: 52 ng/mL]).Clinical symptoms resulted in sweat-testing by Gibson-Cooke pilocarpine iontophoresis at 1 month of age, and the result was positive (102 mmol Cl(-)/L [normal: в