Bronchial hyperreactivity in fresh stage I sarcoidosis.

In order to analyze the mechanism of airways obstruction seen in patients with early sarcoidosis, we have studied the bronchial reactivity in 12 patients with stage I sarcoidosis. The patients were given progressively increasing doses of methacholine to inhale. A fall of more than 35% of the SGaw was taken as the index of response. In 6 out of 12 patients (responders), we observed a dose-response curve similar to that seen in subjects with highly reactive airways. We could not find any difference between responders and nonresponders that could explain the diverse responses to the methacholine. Nevertheless, the modifications in different mechanical parameters showed that the inhaled methacholine induced two types of changes: a change in lung volumes (RV and FVC), observed mainly in the nonresponders, and a change in forced expiratory flows (FEV1, MEF25, and MEF50), observed in the responders. These types of response may suggest a different site of action of the inhaled agent. We conclude that the presence of airways hyperreactivity is frequent in early sarcoidosis and could perhaps explain the incidence of airways obstruction seen in this disease.