Cystic fibrosis

Last updated: Friday, 26, November, 2010
Key InformationAppropriate Tests
Prenatal diagnosisMolecular 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 full molecular genetics cystic fibrosis and chloride - sweat.

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 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 

Sputum - microscopy and culture esp for mucoid Pseudomonas aeruginosa, Burkholderia cepacia and Staphylococcus aureus.


Diabetes mellitus


Salt depletion

See Hyponatraemia.

Infertility (in males)

Congenital bilateral absence of the vas deferens: semen analysis.