Diagnostic studies

(JAMA 2017;318:279)

• Spirometry: ↓ FEV1, ↓ FEV1/FVC, coved flow-volume loop; lung volumes: ± ↑ RV & TLC

⊕ bronchodilator response (↑ FEV1 ≥12% & ≥200 mL) strongly suggestive of asthma

methacholine challenge (↓ FEV1 ≥20%) if PFTs nl: Se >90%

• Allergy suspected → consider checking serum IgE, eos, skin testing/RAST