What does a decreased total lung capacity, FVC and FEV1 on pulmonary function testing indicate?

A decreased total lung capacity, FVC and FEV1 on pulmonary function testing indicates restrictive lung disease, such as pulmonary fibrosis, sarcoidosis, scleroderma and pneumoconiosis.

Restrictive lung diseases decrease both FVC and FEV1, and therefore have a normal FEV1/FVC ratio. In contrast, airway obstruction does not impact lung expansion but does impeded exhalation, thus pulmonary function  tests in obstructive lung disease (emphysema, bronchitis, bronchiectasis, asthma, cystic fibrosis) show normal forced vital capacity (FVC) but lowered forced expiratory volume (FEC1), and therefore lowered FEV1/FVC ratio.

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This post was written by Omar Rifai