Methacholine Challenge Test
Pronunciation: meth-ah-KOH-leen
Also written as: MCT — Methacholine Challenge Test
A bronchoprovocation test in which incremental doses of inhaled methacholine are administered to assess airway hyperresponsiveness, typically used to confirm or exclude asthma.
Full Definition
The methacholine challenge test (MCT) measures the provocative concentration of methacholine required to produce a 20% fall in FEV₁ (PC₂₀), serving as a quantitative index of bronchial hyperresponsiveness. A PC₂₀ ≤ 4 mg/mL is considered strong evidence of airway hyperresponsiveness. In paediatric pulmonology, the test is generally performed in children aged five years and older who can cooperate with spirometry. Editors must ensure 'methacholine' is spelled consistently (not 'metacholine' or 'methycholine') and that PC₂₀ is typeset correctly with subscript '20'.
Usage
Usage note: Spell as 'methacholine' (not 'metacholine'). Ensure PC₂₀ is typeset with a subscript numeral. Expand MCT on first reference.
In Context
- "The methacholine challenge test returned a PC₂₀ of 2 mg/mL, strongly supporting a diagnosis of asthma in the nine-year-old with recurrent wheeze." — Pulmonary function test report
- "A common spelling error in manuscripts is 'metacholine'; editors should standardise to 'methacholine' throughout." — Copyediting style note