Reduced FEV1/FVC ratio

What it means

Abnormally low FEV1/FVC (FEV1 - forced expiratory volume in 1 second; FVC forced vital capacity).

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).

Rare diseases that can present with this5

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Obstructive deficit on pulmonary function test · Obstructive deficit on pulmonary function testing