interpreting methacholine challenge assessment


Provocative Concentration (PC20)Interpretation
>16 mg/mlNormal
4-16 mg/mlBorderline
1-4 mg/mlMild
0.25-1 mg/mlModerate
<0.25 mg/mlMarked/Severe
  • Positive test: If concentration ≤ 4mg/ml achieves drop in FEV1 of 20% or greater