Early diagnosis of cystic fibrosis (CF) is crucial. It allows treatment to start before serious damage occurs, improving quality of life and health outcomes.

Thanks to newborn screening programs, most babies with CF in Australia are diagnosed within weeks of birth. However, some people with milder forms of CF may be diagnosed later in childhood or adulthood.

How is CF diagnosed?

Diagnosing CF involves a combination of tests to confirm the presence of the condition and identify the specific genetic mutations involved.

The main diagnostic tests include:

• Newborn screening: In Australia, all newborns receive a heel prick blood test a few days after birth to screen for CF. If the test suggests a possibility of CF, further testing is arranged.
• Sweat test: The gold standard test for CF diagnosis. It measures the amount of salt in sweat. People with CF have higher salt concentrations because of the faulty CFTR gene.
• Genetic testing: A blood test that identifies mutations in the CFTR gene. This helps confirm diagnosis and guides treatment decisions.

Newborn screening in Australia

Australia introduced newborn screening for CF in the early 2000s. It is now standard practice in every state and territory.

• The screening looks for elevated levels of immunoreactive trypsinogen (IRT), a protein often raised in babies with CF, but can also be high in other situations
• If the screening result is positive, the family is contacted for follow-up testing, including sweat and genetic tests.
• Early diagnosis through screening means treatment can begin quickly, reducing complications and improved health.

Diagnosing CF in older children and adults

Sometimes, CF is not diagnosed through newborn screening. Milder cases, rare mutations, or late-onset symptoms can delay diagnosis.

If CF is suspected due to symptoms, doctors may order a sweat test and genetic testing even in older children or adults.

Why timely diagnosis matters

Starting treatment early can help preserve lung function, improve nutrition, and reduce hospital visits.