Neonatal cystic fibrosis screening is a blood test that looks for increased levels of immunoreactive trypsinogen (IRT), an enzyme produced by the pancreas. The test is performed on newborns to screen for cystic fibrosis (CF).
Cystic fibrosis screening - neonatal; Immunoreactive trypsinogen; IRT test
A sample of blood is either taken from the bottom of the baby's foot of a vein in the arm. A tiny drop of blood is collected onto a piece of filter paper and allowed to dry. The dried blood sample is sent to a lab for analysis.
There is no special preparation needed.
Some states include this test in the routine newborn screening tests that are done before the baby leaves the hospital.
If you live in a state that does not perform routine CF screening, your health care provider will explain whether testing is needed.
The brief feeling of discomfort will probably cause your baby to cry.
Children with CF who are diagnosed early in life and start treatment at a young age may have better nutrition, growth, and lung function. Newborn screening tests allow doctors to identify children with CF before they have symptoms.
Normal values vary from lab to lab. Ask your doctor or testing center for details.
It is important to remember that a positive screening test for cystic fibrosis does not diagnose cystic fibrosis. If your child's test is positive, further tests will be done to confirm the possibility of CF. Not all children with a positive screening IRT test have CF.
Risks associated with the test include:
The IRT level does not indicate the severity of the CF. False-positives may occur.
Farrell PM, Rosenstein BJ, White TB, et al. Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic fibrosis consensus report. Journal of Pediatrics. Aug 2008;153(2).
Review Date: 2/5/2009
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright ©2010 A.D.A.M., Inc., as modified by University of California San Francisco. Any duplication or distribution of the information contained herein is strictly prohibited.
Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.