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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)