Hi there I've posted before. i'm 27 (7 years later after asthma diagnosis), and after having some vocal cord issues from the inhaled cortisteroids, I was lowered to just flovent 250 twice a day. After being on it for about 2-3 months and after a normal PFT they had me do a metacholine challenge with no response. They are saying I can't have asthma because of the negative metacholine challenge. Is this true? What else could I have and what tests can I get to confirm?
The answer to your question depends, to some degree, on what is meant by “no response” to methacholine. Methacholine inhalation challenge is a valid, sensitive test (sensitivity 85%-90%) for diagnosing asthma, including occupational asthma, cough variant asthma, and exercise-induced asthma. The lower the concentration of this substance to cause a 20% fall in a specific pulmonary function test (FEV1), the more likely a positive test. Very low levels that result in a 20% fall, are positive.
The higher the concentration of Methacholine required to cause a fall of 20%, the more likely a negative test; always a negative test when the highest, safely deliverable concentration of methacholine, fails to cause any fall in the FEV! Very high levels that fail to cause a 0-20% fall are negative and in-between, there is a gray area on the test scale where the result may or may not be “positive”. Let’s assume that “no response” equals negative.
And the question is: is this negative challenge valid? Was the test performed valid, consistent with national standards. Is it falsely negative? Or is the diagnosis of asthma incorrect?
If the methacholine challenge were performed shortly after discontinuation of the Flovent, residual beneficial effects of the drug could result in a negative challenge. The beneficial effects of Flovent may persist for days to weeks after discontinuation of the drug, resulting in a negative challenge.
A number of diseases can mimic asthma and result in a negative challenge. An example is a disease called, Eosinophilic Bronchitis which is similar to asthma in clinical presentation (especially cough variant asthma) and responds favorably to inhaled corticosteroids. It is not usually associated with variable airflow obstruction, but wheezing can occur. It is likely that some of the “false-negative” methacholine tests represent eosinophilic bronchitis.
The best advice I can give is for you to seek consultation with a specialist with expertise in the diagnosis of asthma and in the interpretation of positive and negative methacholine challenges. Such specialists are Board Certified Allergists or Pulmonologists. They can speak to your question and provide more specific information about the preceding (above) and more, and how it applies specifically to you and your circumstance.
Copyright 1994-2018MedHelp.All rights reserved. MedHelp is a division of Vitals Consumer Services, LLC.
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. MedHelp 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.