Neonatal cystic fibrosis screening

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Infant blood sample

Overview

Risks

Results

Neonatal cystic fibrosis screening

Definition:

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 todiagnose cystic fibrosis (CF).

Alternative Names:
Cystic fibrosis screening - neonatal; Immunoreactive trypsinogen; IRT test
How the test is performed:

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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.

How to prepare for the test:

Your health care provider will explain the test to you,and youmust sign a consent form before the test. Some states, but not all,includethis testin thenewborn screening exams that are done before the mother and baby leave the hospital.

How the test will feel:

The brief feeling of discomfort will probably cause your baby to cry.

Why the test is performed:

Infants who have CF may haveincreased levels of IRT in their blood for several months after birth. A positive IRT test requires follow uptesting to confirm the diagnosis.

References:
Gross, SD, Boyle, CA, Botkin, JR, et al. Newborn Screening for Cystic Fibrosis:Evaluation of Benefits and Risks and Recommendations for State Newborn Screening Programs. MMWR. 2004;53(RR13);1-36.