Table 2 Diagnostic parameters of extrinsic allergic alveolitis
From: Spotlight on the diagnosis of extrinsic allergic alveolitis (hypersensitivity pneumonitis)
Symptoms: | |
• | Exposure (work)-related cough, chest tightness, dyspnea, fever, with latency period of several hrs |
• | Progressive flu-like symptoms during the exposure periods (e.g. working week) with solution at days off |
• | Dyspnea on exertion |
• | Weight loss in the absence of any other reason |
Clinical/physical examination: | |
• | Fine bibasilar end-inspiratory crackles in advanced chronic forms clubbing and respiratory distress |
Serology: | |
• | Presence of high serum concentrations of antigen-specific IgG antibodies |
Lung function testing: | |
• | FVC < 80% predicted (below lower limit of normal) or |
• | FVC < 70% pred. and/or TL,CO < 80% pred. or |
• | TL,CO < 60% pred. or hypoxemia during exercise |
Radiology: | |
• | Abnormal chest x-ray (nodular, patchy and/or diffuse ground glass pattern) |
• | Abnormal HRCT (ground glass, nodular and/ or patchy opacities, mosaic or UIP pattern |
Serial lung function testing and clinical investigations during antigen exposure periods and days off (for minimal diagnostic changes see SIC below): | |
Specific inhalation challenge (minimal changes after 5-12 hrs): | |
• | FVC and TLC -15% |
• | TL,CO -15% or Pa,O2 – 7 mmHg |
• | New fine bibasilar end-inspiratory crackles |
• | Systemic symptoms (temperature + 1°C and leukocytosis + 2.5 × 109/L) |