| Diagnosis | Suggestive features* |
| COPD | Onset in mid-life; onset in early adulthood should prompt suspicion for alpha-1 antitrypsin deficiency |
| Symptoms slowly progressive | |
| Long smoking history, although can occur in nonsmokers | |
| Dyspnea during exercise | |
| Largely irreversible airflow limitation | |
| Asthma | Onset early in life (often childhood) |
| Symptoms vary from day to day | |
| Symptoms at night/early morning | |
| Allergy, rhinitis, and/or eczema also present | |
| Family history of asthma | |
| Largely reversible airflow limitation | |
| Central airway obstruction (eg, bronchogenic or metastatic cancer, lymphadenopathy, scarring from endotracheal tube) | Monophonic wheeze or stridor |
| Variable inspiratory or fixed slowing on flow volume loop | |
| Chest radiograph often normal | |
| Airway narrowing on three dimensional reconstruction of HRCT scan | |
| Heart failure | Fine basilar crackles on auscultation |
| Chest radiograph shows dilated heart, pulmonary edema | |
| Pulmonary function tests typically indicate volume restriction, but airflow limitation can sometimes be seen | |
| Bronchiectasis | Large volumes of purulent sputum |
| Commonly associated with recurrent or persistent bacterial infection | |
| Coarse crackles on auscultation, clubbing of digits | |
| Chest radiograph/HRCT shows bronchial dilation, bronchial wall thickening | |
| Tuberculosis | Onset all ages |
| Chest radiograph shows upper lung zone scarring and/or calcified granulomata | |
| Positive PPD or IGRA | |
| High local prevalence of tuberculosis | |
| Obliterative bronchiolitis | Onset in younger age, nonsmokers |
| May have history of rheumatoid arthritis or fume exposure | |
| HRCT on expiration shows hypodense areas, mosaic pattern | |
| Diffuse panbronchiolitis | Most patients are male and nonsmokers |
| Highest prevalence in East Asia | |
| Almost all have chronic sinusitis | |
| Chest radiograph and HRCT show diffuse small centrilobular nodular opacities and hyperinflation |
