Pre-bronchodilator FEV1 and force vital capacity are normal. The FEV1/ FVC ratio is at the lower limit of normal. There is a mild reduction in FEF25-75. Lung volumes show an increased total lung capacity, FRC and RV indicating hyperinflation. There is no significant response to inhaled methacholine. Skin prick testing reveals no significant atopy. The results are consistent with some early airway narrowing and hyperinflation.