Airway obstruction Reduced FEV1/FVC ratio 2016-07-02T07:08:44Z Abnormally low FEV1/FVC (FEV1 - forced expiratory volume in 1 second; FVC forced vital capacity). UMLS:C4280729 Obstructive deficit on pulmonary function test Obstructive deficit on pulmonary function testing A low FEV1/FVC ratio indicates an obstructive defect. There are several cutoffs in the literature. The first option is to follow the GOLD criteria, which use a cutoff of less than 70 percent. For patients five to 18 years of age, the National Asthma Education and Prevention Program guideline says that a ratio of less than 85 percent is consistent with an obstructive defect as long as the patient has symptoms consistent with obstructive lung disease. The second option is to follow the ATS criteria, which use the lower limit of normal (LLN) as the cutoff for adults. The LLN is a measurement less than the fifth percentile of spirometry data obtained from the Third National Health and Nutrition Examination Survey (NHANES III). Abnormality on pulmonary function testing