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The University of Chicago Medicine - Comer Children's Hospital

Genetic & Newborn Screening for Cystic Fibrosis

If your baby tested positive for cystic fibrosis (CF) after having the newborn screening test, we're here to help. Our team of specialists from the University of Chicago Cystic Fibrosis Center and the Department of Human Genetics provides the full range of testing and counseling services to help families that may be affected by cystic fibrosis. If a diagnosis of cystic fibrosis is confirmed, our experts can provide advanced, compassionate care to treat this complex, chronic disease.

All birthing hospitals in Illinois offer CF testing as part of the usual newborn screening process.

Before each newborn leaves the hospital, a small amount of blood is collected from the infant to be used for variety of important screening tests. Newborn screening for cystic fibrosis is one of the conditions screened for and has two components:

  • Measurement of immunoreactive trypsinogen (IRT)
  • Assessment of the most common genetic mutations causing CF

Infants with positive newborn screening tests (elevated IRT and one or two common CF mutations) will require prompt follow-up to determine if the child has CF or if he/she is an unaffected carrier for the CF trait. A sweat test is a follow-up test used to determine if the child has CF.

Early detection and treatment of cystic fibrosis leads to improved nutrition and infection control and thus improved overall outcome.

Notification of positive results will go to the child's primary care provider/pediatrician who will then notify the family. Most infants with a presumptive positive newborn screening test will either be affected with CF or will be unaffected carriers of the CF trait.

Pediatricians and clinicians should refer the infant to a qualified Cystic Fibrosis Foundation accredited care center as mandated by Illinois Department of Public Health for confirmatory testing by sweat chloride (quantitative pilocarpine iontophoeresis). This is also referred to as a sweat test. The University of Chicago Medicine has an accredited care center that offers sweat testing and genetic counseling for families with children who have tested positive for the newborn CF test.

Learn more: My Baby has a Positive Newborn CF Screening Result (PDF)

If your child tested positive for the newborn CF screening, he or she will need to have a sweat test to confirm the diagnosis. The sweat test determines the amount of chloride (a component of salt) in sweat.

There are no needles involved in the procedure. In the first part of the test, an electrode is attached to the arm or leg to stimulate sweating. Individuals may feel a tingling sensation in the area or a feeling of warmth. The second part of the test consists of collecting the sweat in a plastic coil. Thirty minutes later, the collected sweat is sent to the hospital laboratory for analysis.

False positive and false negative results are possible with the newborn screening test for CF. The sweat test will help to determine the diagnosis of CF.

There are no restrictions on activity or diet or special preparation before the test. However, one should not apply creams or lotions to the skin 24 hours before the test. All regular feedings and medications may be continued and will have no effect on the test results.

University of Chicago CF Center experts and genetic counselors will meet with the family to discuss the diagnostic test results and any next steps on the same day. If a CF diagnosis is confirmed, our team will provide educational information about CF, as well as guidance on how to find a CF specialist.

If your child does not have CF but is found to be a carrier of the CF gene, our genetic counselors will provide information about being an unaffected carrier.

Learn more: My Baby Is a CF Carrier. What Does that Mean? (PDF)

If your child has had a positive newborn screening test for CF, please contact one of our CF counselors in the Department of Human Genetics at (773) 834-9110 or the University of Chicago Cystic Fibrosis Center office at (773) 702-6178 to schedule an appointment for further testing and genetic counseling.