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Methacholine Challenge Test

A methacholine challenge test is a test that uses a dose of methacholine to narrow your airways and test the reactiveness or responsiveness of your lungs. It can be used to help diagnose if you have asthma. 

A methacholine challenge test is also known as a bronchoprovocation test. 

Preparing for Your Test

The only precautions you should follow to prepare for your test are listed below: 

  • Don’t consume any caffeine. That means no tea, soda, coffee, or chocolate. 
  • Stop taking your inhaler. Your doctor will give you specific instructions about when and how to stop using your inhaler before the test. 

How the Test Works

First, you will be given a breathing test, known as spirometry, to establish a baseline of your lung function.  

You will be asked to inhale a very small dose of methacholine, a drug that can narrow your airways. After you inhale the methacholine, you will take a breathing test, formally known as spirometry. This lets us see how narrow your airways are due to the methacholine. 

This process is repeated again and again, using increasingly smaller doses. The test stops when your lung function drops by only 20% or when you reach the maximum dose, and your lung function doesn’t change. 

During the test, you may experience some chest tightness or coughing. However, most people don’t experience any symptoms. If you do start to experience discomfort, the test will end. 

Reading the Results

If breathing in the methacholine results in a 20% (or more) decrease in your ability to breathe compared to your baseline lung function, your lungs are considered reactive. A reactive diagnosis means that you may have asthma.

If breathing the methacholine doesn’t decrease lung function, you have a responsive result. That means that a diagnosis of asthma is unlikely. 

Risks Associated with the Methacholine Challenge

The test is relatively safe but can cause your airways to tighten. The most commonly seen risk is that you may feel like you are experiencing an asthma attack, and you will feel symptoms such as: 

  • Chest tightness
  • Coughing
  • Wheezing
  • Shortness of breath

If your airways are constricted, you will be given a bronchodilator to relieve the symptoms you are experiencing. 

If you have one or more of the following conditions, you shouldn’t take this test. 

  • Pregnancy
  • Nursing
  • Uncontrolled high blood pressure
  • Recent heart attack 
  • Recent stroke
  • Low lung function when taking the baseline spirometry test

Please let us know if you feel unwell on the day of the test or have a cold or cough.

Methacholine Challenge Test in Portland, Oregon

At West Hills Allergy & Asthma Associates, Dr. Anderson-Cowell has more than two decades of experience diagnosing and treating patients with asthma. 

The methacholine challenge test is one of the many tests that can confirm or deny an asthma diagnosis.   

If you’re looking for expert diagnostic experience and effective treatment history, Dr. Anderson-Cowell can help. For a consultation, please call (503) 297-4779 or request an appointment online.

9701 SW Barnes Road
Suite 130
Portland, Oregon 97225

(503) 297-4779

Monday - Thursday (Closed Friday)
8:00 AM - 5:30 PM

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