Diagnostic Approach to Eosinophilia with Chronic Cough and Laryngitis

Initial Evaluation and Diagnostic Tests

The American Thoracic Society recommends obtaining chest radiograph and spirometry as first-line investigations to exclude structural lung disease and assess for airflow obstruction 3, 1
Spirometry with bronchodilator response is essential to distinguish nonasthmatic eosinophilic bronchitis (NAEB) from asthma, with normal spirometry and no reversibility supporting NAEB diagnosis 1, 5
Methacholine challenge test with a provocative concentration >16 mg/mL helps exclude asthma and supports NAEB diagnosis 1, 5
Induced sputum analysis is the gold standard for confirming eosinophilic airway inflammation, with a differential cell count showing ≥3% eosinophils confirming the diagnosis 5, 2
The European Respiratory Society suggests that alternative diagnostic methods, such as bronchoscopy with bronchoalveolar lavage showing >25% eosinophils, can provide similar diagnostic information if sputum induction is unavailable 1, 6

The American College of Chest Physicians recommends inhaled corticosteroids as first-line therapy for confirmed NAEB, with budesonide 400 μg twice daily for 4 weeks demonstrating efficacy in improving cough sensitivity and reducing sputum eosinophil counts 1, 2
The expected response time to inhaled corticosteroids is within 4 weeks of initiating therapy, with repeat induced sputum analysis recommended to confirm reduction in eosinophil count 1, 6
The American Gastroenterological Association suggests that proton pump inhibitor therapy should be initiated empirically for concurrent gastroesophageal reflux disease (GERD), as it commonly coexists with eosinophilic airway disease and can cause laryngeal inflammation 4, 9