What is the role of methacholine in the workup of patients with asthma symptoms?

Updated: Nov 20, 2020
  • Author: Michael J Morris, MD, FACP, FCCP; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Trained individuals should perform this asthma testing in an appropriate facility and in accordance with the guidelines of the American Thoracic Society published in 1999. [64] Methacholine is administered in incremental doses up to a maximum dose of 16 mg/mL, and a 20% decrease in FEV1, up to the 4 mg/mL level, is considered a positive test result for the presence of bronchial hyperresponsiveness. The presence of airflow obstruction with an FEV1 less than 65-70% at baseline is generally an indication to avoid performing the test.

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