Reduced FEV/FVC and FEV in the Normal Range as a Physiological Variant.

Background: Healthy individuals without respiratory symptoms can sometimes present with low FEV/FVC. The objective of this study was to characterize and compare subjects without symptoms and with reduced FEV/FVC but normal FEV with subjects with mild obstructive lung disease.

Methods: Fifty healthy subjects with FEV/FVC below the fifth percentile of reference values (normal variants) were compared with 52 subjects with asthma and 48 subjects with COPD who had similar FEV/FVC.

Chronic hypersensitivity pneumonitis.

Hypersensitivity pneumonitis (HSP) is a common interstitial lung disease resulting from inhalation of a large variety of antigens by susceptible individuals. The disease is best classified as acute and chronic. Chronic HSP can be fibrosing or not.