The use of methacholine inhalation, methacholine skin testing, distilled water inhalation challenge and eosinophil counts in the evaluation of patients presenting with cough and/or nonwheezing dyspnea.

Twenty-four patients presenting with cough and/or nonwheezing dyspnea were evaluated with methacholine inhalation challenge (MC), distilled water inhalation challenge (DC), intracutaneous tests to varying concentrations of methacholine, total eosinophil counts (TEC), sinus and chest x-rays. We found a statistically significant difference (P less than .005) in the mean TEC in those patients with a positive MC test and those with a negative test. Hyperreactivity of the airways to methacholine in asthmatics is not found in the skin. Distilled water inhalation did not serve to substitute for MC as a test of hyperreactive airways. The TEC is an excellent screening test as a predictor of patients with cough or dyspnea who have hyperreactive airways.