What screening tests are recommended for newborns to detect cystic fibrosis early, and how should I interpret the results?

Recommended screening test for newborns to detect cystic fibrosis early:

• Newborn screening for cystic fibrosis is primarily performed using the blood spot immunoreactive trypsinogen (IRT) test.
• If the IRT test is positive or equivocal, it is followed by confirmatory testing with a sweat chloride test and/or cystic fibrosis gene mutation analysis.
• This approach allows diagnosis in infants with no symptoms, enabling early intervention.

Interpretation of results:

• A positive newborn blood spot IRT test requires referral for a sweat test and gene testing to confirm diagnosis.
• A positive sweat test or identification of one or more cystic fibrosis mutations confirms the diagnosis.
• Equivocal or borderline sweat test results also warrant referral to a specialist cystic fibrosis centre for further assessment.
• In rare cases, cystic fibrosis diagnosis may be based on clinical manifestations even if sweat or gene tests are normal, but this is uncommon.

Early diagnosis through newborn screening allows timely management to prevent or limit symptoms and complications of cystic fibrosis.

All newborns in the UK are offered this screening as part of the Newborn Blood Spot Screening Programme.

Referral to specialist cystic fibrosis centres is recommended for any positive or equivocal test results to ensure appropriate follow-up and care.

Parents and carers should be provided with clear information and support following diagnosis.

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