A methacholine challenge is a breathing test that is the gold standard for diagnosing asthma. You will blow into a spirometer before and after each increasing dose of an inhaled medicine. This test is positive for asthma if the result after the inhaled medicine is 20% lower than it was before the inhaled medicine.
When a person has a positive methacholine challenge, it usually means that person has asthma. However, it can be positive in a person who has hay fever, also called allergic rhinitis, where allergies are causing inflammation of the nose. In addition it can be positive in a person who has chronic obstructive pulmonary disease (COPD), also called emphysema. Most of the time this testing indicates asthma, especially when it is strongly positive.
The methacholine challenge measures the reactivity of the airways of the lungs; that is how twitchy are the airways. The airways are more likely to narrow in response to triggers, such as irritants, infection, exercise, heartburn, cold air, or allergies. The tendency for twitchy airways is an inherited trait. However, the degree of twitchiness varies naturally over time. It can also be dependent upon recent exposures. For example, it may be more positive during the spring if the person is allergic to tree pollens and more positive in the fall if allergic to weeds.
It's generally helpful as a guide on how twitchy your airways are. Some folks who have only exercise-induced asthma do NOT react during the methacholine challenge but are still asthmatics. They may require exercise challenge testing.
Copyright 1994-2016MedHelp International.All rights reserved. MedHelp is a division of Aptus Health.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.