other investigations

Last reviewed 01/2018

Further tests include:

• sputum may reveal:
• the infective organism that triggered the acute attack
• eosinophilia
• Curschmann's spirals (casts of small airways)

• FEV1/FEV:
• usually less than 75%
• improves with bronchodilator administration
• there is usually a fall in FEV with exercise

• blood culture - consider if infection has caused the exacerbation

• hypersensitivity skin tests:
• are not performed in the acute phase
• may identify allergy to specific antigens, e.g. aspergillus, and so be helpful in guiding treatment

• autoantibodies, particularly ANCA if Churg-Strauss syndrome is suspected