Pulmonary function and bronchial reactivity in children after croup.

Ninety-six children who were admitted into hospital with croup 8.5 yr previously were studied to assess lung function, atopic disease, and bronchial reactivity. Although absolute values in pulmonary function showed only small differences, children who have had croup are members of a population that is significantly different from normal children. Thirty-five per cent had heightened bronchial reactivity, as determined by methacholine challenge. There was no increased incidence of atopic disease in the children studied. One can speculate that these children who have had croup may be a population susceptible to developing chronic obstructive airway disease as adults.