A 12 year-old boy develops intermittent shoness of breath over the past 6 months. He is not on any medications and has no significant family history. The vitals are within normal limits and the lungs are clear to auscultation. Lung function tests reveal a FEV1/FVC ratio of 82%. Which of the following would be most helpful in excluding a diagnosis of asthma in this patient?
In pts with asthma the airways are Hyper-responsive and administration of methacholine causes more spasm- METHACHOLINE CHALLENGE TEST. If patient has asthma, it will fuher cause deterioration. So this test is useful for diagnosis.
Absence of peripheral blood eosinophilia
Negative allergy skin tests
Negative methacholine challenge
Normal total serum IgE level
Obstructive Lung Disease