Most people with cystic fibrosis (CF) are diagnosed as babies. In countries such as Austria, Switzerland and the UK, all newborn babies are screened for CF as standard. 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.1,2
There are three commonly practised ways of diagnosing CF:
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 Austria, Switzerland and the UK this test is carried out on all newborns.3,4
Sweat testing – People with CF have more salt in their sweat than usual.5 This test 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 done in the hospital. There are no needles involved, although there may be some tingling or warmth in the area being tested.2
Antenatal testing – A test that can be done early in pregnancy to see if the unborn child has CF. This is usually only used in mothers with a family history of CF.5
1. Cystic Fibrosis Canada. Newly Diagnosed. http://www.cysticfibrosis.ca/about-cf/living-with-cystic-fibrosis/newly-diagnosed/. Accessed June 2016.
2. Cystic Fibrosis Foundation. Testing for Cystic Fibrosis. Available from: http://www.cff.org/AboutCF/Testing/. Accessed June 2016.
3. NHS Choices. Cystic Fibrosis - Diagnosis. Available from: http://www.nhs.uk/conditions/cystic-fibrosis/pages/diagnosis.aspx. Updated May 2014. Accessed June 2016.
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. 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.