Cystic Fibrosis (CF) Diagnosis

Cystic fibrosis is usually diagnosed at a young age


Most people with cystic fibrosis (CF) are diagnosed as babies. In Australia all newborn babies are screened for CF as a standard. 1,2 However, this does not happen everywhere. In countries such as Germany and Italy, routine screening happens in some regions but not others, so indicators such as a family history of CF, or a baby’s skin tasting salty, will prompt further investigations. 3,5

There are three commonly practised ways of diagnosing CF:

1. Newborn testing
A small sample of blood is taken from newborns using a ‘heel-prick’ test. This test is usually done in the hospital, where a few drops of blood from the baby’s heel are placed on a special card, which is sent away to check for a range of genetic conditions. In Australia all newborn babies have this test. 2,3

2. Sweat testing
People with CF have more salt in their sweat than usual. 4 Sweat testing involves stimulating a small area of skin to encourage the sweat glands to produce sweat. This sweat is then collected from the skin surface and analysed to check the salt content. Sweat testing is usually carried out in the hospital. There are no needles involved, although there may be some tingling or warmth in the area being tested. 5


3. Antenatal testing
This test can be carried out early in pregnancy to see if an unborn child has CF. This is usually only used in mothers who have a family history of CF. 4

    1. Welsh MJ, Ramsey BW, Accurso F, Cutting GR. Cystic fibrosis: membrane transport disorders. In: Valle D, Beaudet A, Vogelstein B et al.eds.The Online Metabolic & Molecular Bases of Inherited Disease.The McGraw-Hill Companies Inc; 2004: part 21, chap 201. Available at:

    2. Cystic Fibrosis Australia. Available at:

    3. Cystic Fibrosis Foundation. Testing for Cystic Fibrosis. Available at:

    4. Sosnay P, Siklosi K, Van Goor F et al. Defining the disease liability of variants in the cystic fibrosis transmembrane conductance regulator gene. Nature Genetics. 2013;45(10):1160-1167.

    5. Cystic Fibrosis Foundation. Testing for Cystic Fibrosis – Sweat Test. Available at:

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