Question 7: For an infant with an equivocal sweat chloride following newborn screening, how likely is a diagnosis of cystic fibrosis?

Identification of elevated immunoreactive trypsinogen (IRT) on newborn screening (NBS) precedes follow-up genetic and sweat chloride testing to correctly identify infants with cystic fibrosis (CF). A sweat chloride value of ≥ 60 mmol/L, regardless of genetic mutations, or a value of 30-59 mmol/L with 2 CF-causing mutations in the CF transmembrane conductance regulator (CFTR) gene defines cystic fibrosis. While the advent of NBS has led to improved survival in CF patients [1], it has also given rise to a cohort with d iagnostic uncertainty in 2-4% of screen positive infants [2,3].
Source: Paediatric Respiratory Reviews - Category: Respiratory Medicine Authors: Tags: Cystic Fibrosis Frequently Asked Questions Source Type: research