[The metacholine test for the study of unspecific bronchial hyperreactivity in childhood]

To compare the results between asthmatics with different etiology, to study the bronchial reactivity in nonasthmatics, and verify if 8 mg/ml is a good limit of differentiation between asthmatics and healthy ones, a methacholine test was performed in fourty children distributed in four groups: group I (atopic asthmatics); group II (nonatopic asthmatics); group III (nonsymptomatic brothers of asthmatics) and group IV (healthy controls without IV. The means values of PC20 FEV1 were: Group I, 0.42; familiar antecedents of asthma). In groups I and II were all positives, in group III two cases (20%) and none in group II, 0.64; group III, 7.37, and group IV, 16.4 mg/ml. It is verified pathogenic meaning of the bronchial hyperreactivity in the asthma independently of its etiology, and the satisfactory differentiation between asthmatics and healthy ones with 8 mg/ml as limit of positivity. It is suggested the realization of extensive studies in brothers of asthmatics to determine the usefulness of the test as screening in such children.