Newborn Screening

Cystic fibrosis is a serious, heritable disorder that results in the buildup of a thick mucus around several organs including the lungs. Cystic fibrosis is caused by mutations in the CFTR gene (cystic fibrosis transmembrane conductance regulator), which encodes for a protein responsible for transporting salts in and out of cells. The mutations cause the transport protein to be made incorrectly (or not at all).

People who have a single copy of a disease-causing mutation are considered carriers of the disease; they most likely will not develop symptoms, but may pass the disease-causing mutation to their children. Children who inherit two copies of disease-causing mutations will develop cystic fibrosis.

While there is no cure for cystic fibrosis, there are treatments available that can ease the symptoms. Quality of life is significantly better for patients who receive early care, so early diagnosis is very important.

What is a newborn screen?

In the U.S., Canada, Australia, and in most of Europe, newborn infants are tested for a variety of health conditions before leaving the hospital. One of the diseases tested for is cystic fibrosis.

How is a newborn screen performed?

In the first 24 to 48 hours after birth, a few drops of blood from the infant is collected with a heel prick (a quick jab with a small needle in the baby’s heel). The blood is placed on a card and is analyzed to determine how much immunoreactive trypsinogen (IRT) — a protein commonly elevated in cystic fibrosis — is present. A positive test does not mean the baby has cystic fibrosis as there are several conditions that can cause elevated levels of this protein.

If the first test is positive, the IRT test is repeated three weeks after birth. If the levels of IRT are normal, the infant may be a carrier of cystic fibrosis (meaning they have a single copy of a CFTR mutation), but probably does not have the disease.

If the second test is also positive, it may mean the infant will develop cystic fibrosis. The next step is a sweat test to determine whether they are secreting salts normally, or a genetic test to determine whether the child has mutations in the CFTR gene.

What happens next?

If the newborn screen is positive for any condition tested for, the parents will meet with a genetic counselor who will discuss the results of the tests, and if more tests are needed to confirm the results of the newborn screen.

If additional tests are positive for cystic fibrosis, parents will need to meet with a team of specialists to discuss the care and treatment of their child.


Cystic Fibrosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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