Investigations for secondary causes
Spirometry (FEV1, FVC, PEF) and TLCO
to document baseline lung function
for the measurement and monitoring of severity of disease
presence of bronchodilator response (reversibility)
Sputum sample (microbiology and culture)
identify the presence of bacteria or organisms in the sputum
include mycobacterial culture
persistent Staphylococcus aureus may indicate ABPA or CF
surveillance of sputum microbiology helps guide antibiotic therapy
Pathology
full blood count and differential white cell count – Neutropenia/lymphopenia/lymphocytosismay suggest immune deficiency. Eosinophilia suggests asthma or ABPA
immunodeficiency screening – IgG, IgA, IgM and IgG subclass levels (derived from a venous blood sample). Low immunoglobulins suggest a primary (eg CVID) or secondary immunodeficiency state (see Management Strategies for more information on immunotherapy)
serum total IgE, aspergillus precipitins – IgE less than 1000IU/mL and positive aspergillus precipitins is consisitent with ABPA
connective tissue and vasculitis screening – rheumatoid factor, anti-CCP antibodies, antinuclear antibodies, antineutrophil cytoplasmic antibodies
identifying ABPA – Aspergillus in sputum, total IgE, Aspergillus RAST, Aspergillus precipitins (IgG)
Vaccine responses:
Immune deficiency may be identified by impaired vaccine response to pneumoccocal vaccination and Haemophilus influenzae type B
Bronchoscopy indicated when:
response to treatment is poor
HRCT indicative of mycobacterial infection
disease is localised (to exclude obstruction)
unexplained haemoptysis
Exhaled nasal nitric oxide
indicated if considering primary ciliary dyskinesia. This should be considered in cases of dextrocardia, chronic childhood sinusitis or upper respiratory tract infections
studies of ciliary structure and function should be considered in adults with a history of chronic upper respiratory tract infections or otitis media
Sweat test
to exclude cystic fibrosis – CF needs to be excluded in all patients presenting at < 40 years of age and those > 40 years of age where no other cause is evident and there is persistent isolation of Staphylococcus aureus in the sputum, features of malabsorption, male primary infertility or upper lobe bronchiectasis
Alpha-1 anti-trypsin
Alpha-1 anti-trypsin levels and phenotype testing should be considered in young patients with basal emphysema
See TSANZ Bronchiectasis Guidelines for further information on investigations for secondary causes.