False Negative Cystic Fibrosis Newborn Screen.

The article presents a case of a 22-month-boy who was brought to a pediatric pulmonary division for evaluation of recurrent wheezing and coughing after being hospitalized with pneumonia. He was diagnosed with a negative newborn screen for cystic fibrosis (CF) with an immunoreactive trypsinogen (IRT) 2 days after his birth. He was also diagnosed with pancreatic insufficiency based on stool pancreatic elastase testing and 2 morphologies of Pseudomonas aeruginosa from a pharyngeal respiratory culture. It states that despite normal newborn screening, there is a need to consider diagnosis of CF and sweat testing should be performed. Nevertheless, screening is not a definitive means of diagnosis and is associated with false positives and false negatives.