The investigations of fibrosing alveolitis should include:
- chest radiology
- blood tests:
- ESR usually raised
- anti-nuclear factor positive in about 45%
- rheumatoid factor in about 35% of patients - there is an association with rheumatoid arthritis
- increased gamma-globulin
- CT is sensitive for the diagnosis and monitoring of pulmonary fibrosis
- bronchoscopy and bronchoalveolar lavage:
- neutrophils and/or eosinophils are increased
- lymphocytes may also be raised (may be suggestive of favourable treatment response)
- pulmonary function tests:
- restrictive defect
- lung volumes reduced
- lung compliance reduced
- blood gases are normal until advanced disease when there may be arterial hypoxaemia and hypocapnia
- transfer factor is characteristically reduced
Transbronchial or open lung biopsy allows histological analysis. This is not often indicated because of the sensitivity of diagnosis via CT scan.