Every state's CF newborn screening program begins with a blood test from the baby to check the levels of a chemical made by the pancreas called immunoreactive trypsinogent, or IRT. Some states only test IRT levels on the first blood test. These are called IRT-only states. Other states conduct both an IRT and a DNA test. These are called IRT-DNA states.
IRT-Only States
If your baby was born in a state where they only test IRT levels on the first blood test, he or she will need to have the IRT test repeated at your pediatrician's office.
In many IRT-only states, all babies routinely have a repeat newborn screening test (blood test) when they are about 2 weeks old.
If the IRT level remains high on the second test, you will be asked to bring your baby to a CF Foundation-accredited care center for a sweat test to find out whether or not your baby has CF.
IRT-DNA States
If your baby was born in a state where they conduct both an IRT and a DNA test, he or she will automatically have a blood test to check for mutations or changes in the CF gene. This newborn screening method provides more information about how likely it is that your baby has CF. It is important to remember that even this DNA testing is still only a "screen" for CF. It is not a diagnosis, which can only be confirmed with a sweat test.
IRT-DNA testing will not only show your baby's IRT levels but also indicate whether the baby may be a carrier of the CF gene (which means he or she has only one CF gene mutation).
If you have questions about newborn screening or genetic testing for CF, please contact a CF Foundation-accredited care center or talk with your doctor.