How are results of methacholine challenge testing expressed?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Results are presented as both a table of spirometry parameters for each stage of the challenge and as a dose-response curve plotting the fall in FEV1 against the methacholine concentration or the cumulative dose delivered during the challenge. The reporting of the PC20 or PD20 (provocative concentration or dose in mg/mL or milligrams, respectively, causing a 20% fall in FEV1 from baseline) is the usual method of expressing the outcome of the challenge test.

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