Exercise-induced asthma in children with intrinsic and extrinsic asthma.

The significance of intrinsic asthma as a diagnosis has been questioned since, except for the lack of evidence of allergy, there is no pathophysiologic distinction from extrinsic asthma. Following a standardized exercise stress, allergic (extrinsic) asthmatics respond with more severe asthma than do nonallergic (intrinsic) asthmatics. The incidence of significant exercise-induced asthma is greater in a group of extrinsic asthmatics than in intrinsic asthmatics. Extrinsic asthmatics show increased airway sensitivity during a significant pollen season.