Version August 2025
| Diagnosis | Clinical features | Testing |
| Allergic bronchopulmonary aspergillosis | History of asthma or cystic fibrosis Cough productive of phlegm with "bronchial casts" | Eosinophilia: >500 cells/microL IgE: >500 international units/mL Elevated serum IgE (±IgG) levels against Aspergillus fumigatus HRCT: mucous plugging, proximal bronchiectasis |
| Cardiac disease | Crackles or wheezes | Elevated B-type natriuretic peptide Chest imaging: increased interstitial opacities, ±cardiomegaly Echocardiogram: abnormal cardiac function |
| Chronic eosinophilic pneumonia | Asthma predates or develops in over 50% of patients Fever, weight loss, and night sweats are common | Peripheral blood: ±eosinophilia Chest imaging: bilateral peripheral opacities BAL: eosinophilia >40% |
| Eosinophilic granulomatosis polyangiitis (Churg Strauss) | Cutaneous, neurologic, or other evidence vasculitis Paranasal sinus disease | ANCA: positive in 30 to 40% of patients Eosinophilia: >1000 cells/microL Chest imaging: patchy ground-glass opacities and consolidations Biopsy: granulomatous angiitis |
| COPD | Smoking history | PFTs: irreversible airflow obstruction and sometimes low DLCO |
| GERD | May complain of chest tightness/restriction or nocturnal choking | Response to empiric treatment with PPI pH probe monitoring: acid reflux Spirometry normal, methacholine negative* |
| Obstructive sleep apnea | Daytime hypersomnolence Nocturnal choking Snoring | Polysomnogram: elevated apnea hypopnea index |
| Tobacco smoke exposure | History | |
| Inducible laryngeal obstruction (vocal cord dysfunction) | Hoarseness/stridor (can be inspiratory and/or expiratory) Symptoms provoked by exercise | Flow volume loop: slowing on inspiration Direct laryngoscopy (possibly during exercise or methacholine challenge): abnormal cord motion |
ANCA: antineutrophil cytoplasmic antibodies; BAL: bronchoalveolar lavage; CTD: connective tissue disease; DLCO: diffusing capacity; GERD: gastroesophageal reflux disease; HRCT: high resolution computed tomography; PFTs: pulmonary function testing; PPI: proton pump inhibitor.
* GERD can also coexist with asthma in which case methacholine challenge would be positive.
