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Updated: Feb 2, 2026
Breath Collection from Children for Disease Biomarker Discovery
Published on: February 14, 2019
Biomarkers for Recurrent Wheezing and Asthma in Preschool Children
Yong Ju Lee1, Takao Fujisawa2, Chang Keun Kim3,4
1Department of Pediatrics, Hallym University Kangnam Sacred Heart Hospital, Seoul, Korea.
Insights
Diagnosing asthma in preschoolers is challenging due to their inability to perform tests. Non-invasive biomarkers like serum eosinophil-derived neurotoxin (EDN) show promise for identifying asthma and recurrent wheezing in this age group.
Area of Science:
- Pediatric Pulmonology
- Biomarker Discovery
- Allergy and Immunology
Background:
- Asthma diagnosis in preschool children is difficult due to lack of cooperation with spirometry and invasive tests.
- Wheezing is common in preschoolers, but not all cases indicate asthma, necessitating reliable diagnostic methods.
- Current diagnostic methods are insufficient for preschool-aged children, highlighting the need for non-invasive biomarkers.
Purpose of the Study:
- To review non-invasive biomarkers for assessing asthma in preschool children.
- To evaluate the potential of easily obtainable biological specimens (blood, exhaled breath, urine) for asthma diagnosis.
- To identify promising biomarkers for diagnosing asthma in young children who cannot undergo standard testing.
Main Methods:
- Literature review of studies on non-invasive biomarkers for asthma in preschool children.
- Analysis of biomarkers found in blood (eosinophils, eosinophil cationic protein, eosinophil-derived neurotoxin [EDN]), exhaled breath (nitric oxide, volatile organic compounds, cytokines), and exhaled breath condensate (EBC pH).
- Evaluation of the standardization and validation status of identified biomarkers for clinical use in this age group.
Main Results:
- Blood biomarkers like eosinophils and EDN can indicate airway eosinophilic inflammation.
- Fraction of exhaled nitric oxide is standardized for older individuals but not yet for preschoolers.
- Exhaled breath condensate (EBC) pH and its cytokines show potential but require further validation; serum EDN is a promising marker for recurrent wheezing and asthma.
Conclusions:
- No single non-invasive biomarker is currently ideal for diagnosing asthma in preschool children.
- Standardized methods for sample collection from uncooperative children are needed for clinical application.
- Serum EDN shows promise as a valuable biomarker for identifying asthma and recurrent wheezing in preschool-aged children, warranting further research.
Abstract:
Wheezing is one of the characteristic symptoms of asthma, but all preschool children with wheezing are not diagnosed with asthma. Preschool children are not cooperative enough to participate in spirometry and invasive tests. Thus, there is no conventional method to diagnose asthma in preschool children. We reviewed studies on non-invasive biomarkers for assessing asthma in preschool children. Specimens that can be easily obtained by non-invasive methods are blood, exhaled breath and urine. Eosinophils, eosinophil cationic protein and eosinophil-derived neurotoxin (EDN) in blood are helpful in evaluating eosinophilic inflammation of the airways. Exhaled breath contains nitric oxide, volatile organic compounds, various cytokines and mediators as analytical components. Fraction of exhaled nitric oxide has been used to assess the degree of eosinophil inflammation and has been standardized in school-age children and adults, but not yet in preschool children. Exhaled breath condensate (EBC) pH and various cytokines/mediators that are detected in EBC seem to be promising biomarkers for assessing asthma, but need more standardization and validation. There are several biomarkers useful for assessing asthma, but none are ideal. Some biomarkers need standardized methods of obtaining samples from uncooperative preschool children for clinical use and require sufficient validation. Recently, another activated eosinophil marker, serum EDN, has shown promising results as a biomarker for recurrent wheezing and asthma in preschool children.
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