Is the demonstration of bronchial hyperreactivity the sine qua non for diagnosing symptomatic bronchial asthma?

Bronchial hyperreactivity, a fundamental feature of bronchial asthma, is universally present in patients with symptomatic asthma. It can be reliably and safely demonstrated in the pulmonary function laboratory through pharmacological bronchoprovocation challenge testing. Furthermore, in the patient suspected of having symptomatic asthma, the laboratory determination of the presence of bronchial hyperreactivity is diagnostically of greater predictive value than findings on history, physical examination, routine spirometry, or the measurement of the total blood eosinophil count.