Bronchoprovocation in children.

Bronchial hyperresponsiveness (BHR) is a major feature of asthma that is determined by both genetic and environmental factors. The assessment of BHR can be a valuable means of assessing asthma severity and also response to therapy. BHR can be measured with a variety of provocative agents including exercise, methacholine, histamine, hypotonic and hypertonic saline and cold air. Methacholine and histamine challenges have been well studied and standardized. They are extremely sensitive indicators of BHR, but this is not synonymous with asthma. This requires that the physician interprets the clinical significance of test results with caution.