How are neonates screened for cystic fibrosis (CF)?

Updated: Oct 22, 2019
  • Author: Girish D Sharma, MD, FCCP, FAAP; Chief Editor: Kenan Haver, MD  more...
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Newborn screening for CF is universally required in the United States. All screening algorithms in current use in the United States rely on testing for immunoreactive trypsinogen (IRT) as the primary screen for cystic fibrosis. [31] The presence of high levels of IRT, a pancreatic protein typically elevated in infants with cystic fibrosis, warrants second level testing in the form of repeat IRT testing, DNA testing, or both.

A 2008 study from Massachusetts noted a decreasing incidence of cystic fibrosis identified by newborn screening, possibly resulting from more widespread preconception identification of cystic fibrosis carriers. [32] CFTR related metabolic syndrome (CRMS) is used to describe infants identified to have elevated levels of immunoreactive trypsinogen on newborn CF screening, have sweat chloride value of less than 60 mmol/L; have two CFTR mutations, at least one of which is not clearly categorized as CF causing and thus do not meet the Cystic Fibrosis Foundation guidelines for CF diagnosis. The Cystic Fibrosis Foundation published guidelines for the management of such infants. [33]

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