What is a methacholine challenge test?
A methacholine challenge test evaluates your lung function and the reactivity (narrowing or tightening) of your airways. It helps diagnose and monitor asthma, a chronic lung disease marked by acute flare-ups of inflammation and swelling of the airways in the lungs.
A methacholine challenge test is a type of bronchoprovocation test, which measures lung function after exposure to factors that commonly trigger wheezing and other asthma symptoms. A methacholine challenge test involves inhaling a mist that contains methacholine, a substance that causes lung constriction in people with asthma.
A methacholine challenge test is only one method to diagnose asthma. Discuss all of your testing methods with your doctor to understand which options are right for you.
Other procedures that may be performed
Your doctor will likely recommend one or more other pulmonary or lung function tests to diagnose asthma and monitor your condition. Other pulmonary function tests include:
- Arterial blood gas test to measure oxygen and carbon dioxide levels and other factors in the blood
- Body plethysmography to determine how much air is present in your lungs when you take a deep breath and how much air is left in your lungs after you exhale as much as you can. A methacholine challenge test and other pulmonary function tests can be done at the same time as a body plethysmography using the same equipment.
- Lung diffusion capacity to measure how well oxygen moves into your blood from your lungs
- Other bronchoprovocation tests to measure lung function after exposure to factors that commonly trigger asthma. These tests use exercise, cold air, or histamine to trigger lung constriction and wheezing.
- Peak expiratory flow to measure the speed of exhaling and lung constriction. People with asthma use this test routinely to monitor their asthma control at home.
- Pulse oximetry to measure oxygen levels in the blood
- Spirometry to measure the amount of air and the rate that you inhale and exhale
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Bronchoprovocation testing. Wolters Kluwer Health. http://www.uptodate.com/contents/bronchoprovocation-testing. Accessed June 12, 2013.
Methacholine Challenge Testing: Identifying Its Diagnostic Role, Testing, Coding, and Reimbursement. American College of Chest Physicians. http://journal.publications.chestnet.org/article.aspx?articleid=1085169#Contraindications. Accessed June 12, 2013.
Pulmonary Function Test: Methacholine Challenge Test. Cincinnati Children’s Hospital Medical Center. http://www.cincinnatichildrens.org/health/p/pulmonarytest-methacoline/. Accessed June 12, 2013.
When should a methacholinechallenge be ordered for a patientwith suspected asthma? Cleveland Clinic. http://www.clevelandclinicmeded.com/medicalpubs/ccjm/January2008/swartz.htm. Accessed June 12, 2013.