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Updated: Aug 18, 2026
Quantitative Autonomic Testing
Published on: July 19, 2011
Sweat-testing in preterm and full-term infants less than 6 weeks of age
Warren Eng1, Vicky A LeGrys, Michael S Schechter
1Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7145, USA.
Insights
Successful sweat testing for cystic fibrosis (CF) diagnosis in infants requires careful consideration of infant characteristics. Factors like African-American race and postmenstrual age under 36 weeks significantly impact sweat collection success.
Area of Science:
- Pediatrics
- Medical Diagnostics
- Genetics
Background:
- Cystic Fibrosis (CF) diagnosis in infants relies on sweat testing.
- Optimizing sweat collection in neonates and young infants is crucial for timely diagnosis.
Purpose of the Study:
- To identify infant characteristics influencing successful sweat collection for CF diagnosis.
- To determine factors affecting sweat chloride concentrations in infants.
Main Methods:
- Retrospective chart review of 119 sweat tests from 103 infants (preterm and full-term) aged 6 weeks or younger.
- Bivariate and multivariate regression analyses to identify predictors of sweat test success and chloride levels.
Main Results:
- Adequate sweat for analysis was obtained in 73.8% of initial attempts.
- Increased odds of insufficient sweat (QNS) were associated with African-American race, weight < 2,000g, preterm birth, and postmenstrual age (PMA) < 36 weeks.
- Multivariable analysis identified African-American race and PMA < 36 weeks as significant predictors of QNS. Sweat chloride concentration in non-CF infants inversely correlated with gestational age and age at testing.
Conclusions:
- Reliable sweat collection is feasible in infants ≥36 weeks PMA, >2,000g, and >3 days postnatal age.
- Maturational factors have a minor influence on sweat chloride concentration.
- Early identification of factors predicting sweat test success aids in optimizing diagnostic procedures for infants.
Abstract:
Our objective was to examine the characteristics of preterm and full-term infants < or = 6 weeks old that influence the success of obtaining sufficient sweat for diagnosis of CF, and corresponding sweat chloride concentrations. A retrospective chart review of 119 sweat tests was performed on 103 preterm and full-term infants < or = 6 weeks of age. Bivariate and multivariate regression analyses were used to determine the predictors of successful sweat testing and characteristics influencing sweat chloride concentrations. Adequate amounts of sweat (> or = 75 mg) were obtained for analysis in 73.8% of initial attempts in the infant group. The following characteristics were associated with increased odds of obtaining a quantity not sufficient (QNS) for sweat chloride concentration measurement: African-American race, infant weight < 2,000 g, preterm birth, and postmenstrual age (PMA) < 36 weeks. With a multivariable logistic model, the only significant predictors were African-American race (7.3, 2.4-21.7) and PMA < 36 weeks (17.9, 4.2-75.9). Sweat chloride concentration in non-CF individuals is inversely related to both gestational age and age at testing, and this effect is additive in a linear regression model. In conclusion, sweat collection can be reliably performed in infants > or = 36 weeks postmenstrual age, > 2,000 g, and > 3 days postnatal age. Maturational factors have a mild impact on sweat chloride concentration.
