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Methacholine and FeNO Measurement in Patients with Habit Cough
Sandra Woelke1, Alexandra Szelenyi1, Melanie Dreßler1
1Department for Children and Adolescence, Division of Allergy, Pulmonology and Cystic fibrosis, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
Insights
Diagnosing habit cough in children can be challenging. Normal fractional exhaled nitric oxide (FeNO) and methacholine challenge tests (MCT) support habit cough, but elevated results require ruling out other conditions.
Area of Science:
- Pediatric Pulmonology
- Allergology
- Clinical Diagnosis
Background:
- Chronic cough is a common pediatric symptom, posing diagnostic challenges, particularly when no organic cause is identified, as in habit cough.
- Differentiating habit cough from other conditions is crucial for appropriate management in children.
Purpose of the Study:
- To investigate the diagnostic utility of normal fractional exhaled nitric oxide (FeNO) and methacholine challenge tests (MCT) in confirming habit cough in children.
- To determine the implications of abnormal FeNO and MCT results in the context of suspected habit cough.
Main Methods:
- Retrospective analysis of outpatient charts for children with chronic cough (duration > 4 weeks).
- Diagnostic workup included skin prick tests (SPT), FeNO measurements, spirometry, and MCT.
- Evaluation focused on the value of normal FeNO and MCT in diagnosing habit cough.
Main Results:
- Out of 482 children with chronic cough, 99 were suspected of having habit cough; 55 had complete data.
- 33 patients (60%) were SPT negative, while 22 (40%) showed sensitization to allergens.
- Five patients had elevated FeNO (≥20 ppb), and three exhibited severe bronchial hyperresponsiveness (<0.1 mg/mL MCT), questioning the habit cough diagnosis.
Conclusions:
- Normal FeNO and MCT results can aid in confirming a clinical diagnosis of habit cough.
- However, habit cough may coexist with positive MCT and/or elevated FeNO.
- Elevated FeNO and severe bronchial hyperresponsiveness necessitate ruling out cough variant asthma and eosinophilic bronchitis.
Background:
Chronic cough is one of the most common symptoms in childhood. Making a definite diagnosis is a challenge for all pediatricians especially in patients when cough is without an organic cause like in habit cough.
Patients And Methods:
In this retrospective analysis, all electronic outpatient charts of the Division of Allergology and Pneumology, between January 1, 2010 and December 31, 2019 were reviewed in order to study all children with potential habit cough. All children underwent the following diagnostic algorithms, skin prick test (SPT), measurement of fractional exhaled nitric oxide (FeNO), spirometry and methacholine challenge test (MCT). The value of a normal MCT and FeNO measurement for diagnosing habit cough was investigated.
Results:
The chart review revealed 482 patients with chronic cough>4 weeks. Of these, 99 (20.5%) with suspected habit cough were collected. 13 patients had to be excluded for other diagnosis and a complete data set was available in 55 patients. 33 (60.0%) of 55 patients were SPT negative and 22 (40.0%) had sensitization to common allergens. Five patients had elevated FeNO≥20 ppb and three showed severe bronchial hyperresponsiveness<0.1 mg methacholine, challenging the diagnosis of habit cough.
Conclusion:
A normal FeNO and MCT can help confirm the clinical diagnosis of habit cough. However, in patients with positive MCT and/or elevated FeNO habit cough can be present. Especially in patients with elevated FeNO and severe BHR cough variant asthma and eosinophilic bronchitis have to be ruled out.
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