What are technical considerations for the performance of methacholine challenge testing?

Updated: May 14, 2020
  • Author: Kevin McCarthy, RPFT; Chief Editor: Nader Kamangar, MD, FACP, FCCP, FCCM  more...
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Spurious nonreproducible decrements of expiratory airflow should not be considered valid. Continuation of the challenge beyond 25 mg/mL has little clinical value because responses of some healthy patients who are nonasthmatic begin at this level.

Failure to demonstrate bronchial hyperreactivity does not totally exclude asthma, particularly asthma triggered by specific exposure to chemicals (eg, methylene diisocyanate, toluene diisocyanate).

A positive methacholine challenge test does not by itself indicate the presence of asthma. Nonspecific bronchial hyperreactivity is characteristic of asthma but occurs after a viral respiratory illness, with resolution taking up to several months.

Nonspecific bronchial hyperreactivity also can be found in chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis.

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