How can doctors distinguish between a diagnosis of copd and asthma?

Breathing Tests: COPD and asthma both present with airway obstruction however timing of presentation is helpful to determine cause. Asthma usually presents in childhood but can present in adults, however COPD usually presents only in adults over the age of 40 who are current or former smokers. Spirometry or Pulmonary Function Testing can differentiate between these two conditions. See an Allergist or Pulmonologist