Screening for cystic fibrosis is not often done with newborns; in fact, most individuals with this condition are diagnosed by age two. Tests for cystic fibrosis in infants can include a sweat test, in which the salt content of the infant’s sweat is measured—higher sodium chloride levels may be indicative of cystic fibrosis. For babies who do not produce sufficient sweat, blood tests may be used. Babies may also be given what is called an immunoreactive trypsinogen (IRT) test; high levels of IRT indicate the possible of cystic fibrosis and call for more tests. In addition, genetic testing of the blood may be used to see if a person has inherited or is a carrier of the disease.
If both the mother and father are (or suspect that they are) carriers of cystic fibrosis, the parents may wish to have the fetus undergo prenatal testing; a cell sample is taken through amniocentesis or chorionic villus sampling, and the cells are tested for cystic fibrosis.
Other tests look for problems associated with cystic fibrosis, including:
- Imaging tests such as a chest x-ray or CT scan
- Lung function tests
- Fecal fat test
- Sputum culture
- Organ function tests, e.g., of pancreatic function