Cystic fibrosis

Key Information

Appropriate Tests



Pre-pregnancy screening

CF genotyping assay.

Prenatal diagnosis

Molecular genetics (CVS or amniotic cells) for mutation identification, DNA polymorphisms in families without previously identified mutations.

Neonatal screening

Patients with initial positive results should be followed up with Chloride sweat and full Molecular genetics for cystic fibrosis. 

See also Neonatal screen.

Symptomatic patients, including meconium ileus

Molecular genetics and Chloride sweat.

If there is a strong clinical suspicion, in a patient with normal sweat chloride and/or initially normal molecular genetics studies, rare mutations should be sought.

In infants presenting with meconium ileus, blood trypsinogen (neonatal screening) may be normal, so sweat electrolytes and molecular genetics must always be performed.



Chronic respiratory infection, especially

  • Bronchiectasis

MCS sputum or cough swab especially for mucoid Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus.


Faecal fat microscopy, faecal elastase and Chymotrypsin faeces.

Diabetes mellitus

Glycated haemoglobin (HbA1c)


Serum/plasma hepatic transaminase profile, Albumin; INR

Salt depletion

See Hyponatraemia.

Infertility (male and female)

Congenital bilateral absence of the vas deferens. Semen analysis - fertility.



Go Back

Page last updated:

Copyright © 2021 RCPA. All rights reserved.