Non-specific bronchial airway hyperreactivity and the diagnosis of asthma.

: In very mild and atypical cases of asthma, highly discriminative tests are needed to make the diagnosis. To demonstrate this, measurement of non-specific bronchial airway hyperreactivity by means of standardized bronchial inhalation challenge tests with histamine and methacholine were performed in 10 very mild asthmatic and nine normal control subjects; both groups included Nigerians who were temporarily resident in London at the time of the study. Bronchial reactivity was expressed as the provocative concentration of the agents causing a 20% fall in forced expiratory volume in 1 sec (PC20FEV1); higher values indicating lower levels of non-specific bronchial reactivity. The level of non-specific bronchial reactivity in these very mild asthmatics, whose baseline physiological data were not different from those in normals, was found to be 18-29 times higher than the normal control subjects. These tests very effectively discriminated between asthmatic and normal control subjects. With available resources it should be possible to study a large number of Nigerians in their own environment.