Cystic Fibrosis Newborn Screening (NBS)

Screening for CF

Why is it important to screen for CF at birth?
What does the CF newborn screening test check for?
Do all states do NBS for CF?
How does CF newborn screening differ by state?
How can I tell which screening method my state uses, IRT-only or IRT-DNA?
For IRT-only states, how was my baby screened?
For IRT-DNA states, how was my baby screened?
Does newborn screening find all babies who are CF carriers (meaning they have only one CF gene mutation)?

Why is it important to screen for cystic fibrosis (CF) at birth?

It’s important to diagnose CF early, so that CF health care providers can help parents learn ways to keep their child as healthy as possible and delay problems related to CF. Research shows that children who receive CF care early in life have better nutrition and are healthier than those who are diagnosed later. Good nutrition in CF is important for overall health and well-being.

What does the CF newborn screening test check for?

Most babies with a high IRT do not have CF, since a number of things can cause a high IRT, including prematurity. A positive or abnormal IRT result simply means your baby could have CF, and another test is needed.

The CF screening test checks for a chemical made by the pancreas, an organ that helps with digestion. This chemical is called immunoreactive trypsinogen, or IRT. It is normally found in small amounts in the body.

When the pancreas is stressed before a baby is born, more IRT is released into the baby’s blood. The IRT can be high if a baby is premature or had a stressful delivery, or for other reasons. The IRT tends to be high in people who have CF.

However, most states now do a second blood test on the first newborn screening blood sample to check for changes in the gene that causes cystic fibrosis.

Do all states do NBS for CF?

Yes. Each state's CF newborn screening program begins with a test on blood from a baby. In some states, a second blood test is done when your baby is about two weeks old to find out if the IRT level is still high. This is called an IRT-only method of newborn screening.

How does CF newborn screening differ by state?

While some states measure only the amount of IRT, when a newborn has a high IRT, most states then check for changes in the gene that causes cystic fibrosis. In fact, 90 percent of newborns in the U.S. with a high IRT have this second screening.

Called the IRT-DNA method, this type of newborn screening provides more information about how likely it is that a 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.

Your baby’s newborn screening report will show whether genetic testing was done and what the results are.

How can I tell which screening method my state uses: IRT-only or IRT-DNA?

Click on the state in the map below to see the newborn screening method used in the state where your baby was born.

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For IRT-only states, how was my baby screened?

If your baby was born in an IRT-only state and had a high IRT level 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 two weeks old.

If the IRT 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.

For IRT-DNA states, how was my baby screened?

If your baby was born in an IRT-DNA state and had a high IRT level on the first blood test, he or she will automatically have a blood test to check for changes, or mutations, in the CF gene.

Based on your baby’s newborn screening results, you may be asked to bring your baby to a CF Foundation-accredited care center for sweat testing.

Knowing how many CF gene mutations were found in your baby is very helpful in establishing how likely it is that your baby has CF. Your baby’s newborn screening report may list how many and what kind of mutations were found on the newborn screening result.

Babies with two CF gene mutations are very likely to have CF. However, your baby may have CFTR-related metabolic syndrome (CRMS). You can learn more by visiting the CRMS section.
Babies with only one gene mutation found on a newborn screening result probably do not have CF. A high IRT level sometimes occurs when a baby is a carrier of CF.
Not all CF carriers (people who have only one CF gene mutation) will be found with the blood test that measures IRT. Most CF carriers will have normal IRT levels, and will not be identified by newborn screening.
Babies with no CF gene mutations but who have a very high IRT level are unlikely to have CF. As a precaution, the health care provider might ask parents to bring the baby to a CF Foundation-accredited care center for a sweat test.

Does newborn screening find all babies who are CF carriers (meaning they have only one CF gene mutation)?

No. CF newborn screening finds babies who have cystic fibrosis. However, some screenings do DNA testing. The DNA test may find some but not all babies who are CF carriers. If you have questions, please contact a CF Foundation-accredited care center or talk with your doctor.

Updated 1/11/2012