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Sweat testing infants detected by cystic fibrosis newborn screening
Richard B Parad1, Anne Marie Comeau, Henry L Dorkin
1New England Newborn Screening Program of University of Massachusetts Medical School, MA 02130, USA. richard.parad@umassmed.edu
Insights
Early sweat testing for cystic fibrosis (CF) newborn screening (NBS) can yield insufficient sweat samples. Effective CF NBS sweat testing is generally successful after two weeks of age.
Area of Science:
- Neonatal screening
- Genetic disorder diagnostics
- Biochemical testing
Background:
- Cystic Fibrosis (CF) newborn screening (NBS) is crucial for early diagnosis.
- Pilocarpine iontophoresis (sweat testing) is a standard method for CF diagnosis.
- Understanding the limitations of early sweat testing is vital for effective NBS programs.
Purpose of the Study:
- To describe and define the limitations of early pilocarpine iontophoresis for CF newborn screening.
- To establish optimal timing for sweat testing in newborns identified through CF NBS.
Main Methods:
- Analysis of population-based results from newborns identified as positive through CF NBS.
- Evaluation of sweat test success rates and sweat chloride levels based on infant age.
Main Results:
- Insufficient sweat quantity is a significant limitation of early sweat testing (before 2 weeks of age).
- Sweat chloride levels demonstrate a decline during the first weeks of life.
- Confirmed CF carriers exhibit higher sweat chloride concentrations compared to non-carriers.
Conclusions:
- Pilocarpine iontophoresis for CF NBS can be effectively performed after two weeks of age.
- Testing newborns earlier than two weeks increases the risk of insufficient sweat sample collection, potentially impacting diagnostic accuracy.
Objective:
Describe and define limitations of early pilocarpine iontophoresis (sweat testing) for cystic fibrosis (CF) newborn screening (NBS).
Study Design:
Population-based results from follow-up of CF NBS-positive newborns.
Results:
Insufficient quantity of sweat is more likely if the sweat test is done too early, but testing is generally successful after 2 weeks of age. Sweat chloride levels drop over the first weeks of life. CF carriers have higher sweat chloride concentrations than non-carriers.
Conclusions:
Sweat testing can be performed effectively after 2 weeks of age for CF NBS-positive newborns. Earlier testing has a higher risk of insufficient sweat for completing testing.
