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Table 3 Summary of diagnostic criteria

From: Spotlight on the diagnosis of extrinsic allergic alveolitis (hypersensitivity pneumonitis)

Routine, basic diagnostics:
Case history: Exposure to relevant antigen(s)
Exposure-related respiratory and systemic symptoms
Specific IgG antibodies to relevant antigens (i.e. antigen-HSA-conjugates)
Bibasilar end-inspiratory crackles (lower lung)
Lung nodular, patchy and/or ground glass pattern in chest x-ray or HRCT
Restrictive ventilation pattern (FVC, TLC) and reduced gas exchange parameters (TL,CO; Pa,O2)
Facultative diagnostic parameter.
If not all of the before-mentioned parameters are fulfilled at least one additional positive parameter is needed
Serial lung function testing during antigen exposure periods and days off (exhibiting changes as outlined under SIC as well as restitution of symptoms and impaired lung function during days off) or
specific inhalative challenge test (exhibiting changes as outlined in Table 2)
BAL showing lymphocytosis with ratio of CD4/CD8 < 1 or
typical histopathological findings
  1. Note: we do not recommend the evaluation point system, but rather a careful valuation of the clinical findings and laboratory data in each individual case (see above).