A spirometry test with reversibility measures lung function (FEV1, FVC) before and after a bronchodilator to detect airflow obstruction and its reversibility. Baseline spirometry is done, a bronchodilator is given, then measurements are repeated after about 10–15 minutes. A significant rise (commonly ≥12% and ≥200 mL in FEV1) suggests reversible airway disease, often seen in asthma.

Reversibility in asthma describes improvement in airflow after treatment, typically measured by spirometry. A significant response is an increase in FEV1 of at least 12% and 200 mL (or a similar rise in peak expiratory flow) after a bronchodilator or anti-inflammatory therapy. Demonstrable reversibility supports an asthma diagnosis and helps distinguish it from fixed obstructive conditions like COPD.

COPD is generally not fully reversible on spirometry. Diagnosis requires a post-bronchodilator FEV1/FVC below 0.70 (or below the lower limit of normal), indicating persistent airflow limitation. Some patients show partial bronchodilator response, but improvements that do not normalize spirometry still support COPD rather than fully reversible asthma. Serial testing and clinical context guide severity assessment and management.

A positive reversibility test occurs when spirometry shows a significant rise in FEV1 after an inhaled bronchodilator—commonly an increase of ≥12% and ≥200 mL measured about 10–15 minutes later. This indicates reversible airflow obstruction, supporting asthma rather than fixed COPD, and can help guide diagnosis and treatment decisions when combined with clinical assessment.

If you "fail" a spirometry test—meaning results are abnormal—it suggests airflow obstruction or restriction and could indicate asthma, COPD, or other lung disease. Your clinician will usually repeat testing, assess bronchodilator response, and may order lung volumes, diffusion capacity, or imaging. Treatment (inhalers, smoking cessation) and specialist referral with ongoing monitoring may follow. Poor effort or technique can also cause abnormal results.

A normal spirometry shows FEV1 and FVC values at or above about 80% of the predicted value for age, sex, height and ethnicity, with an FEV1/FVC ratio at or above roughly 0.70 (or above the test’s lower limit of normal for the person). There should be no significant bronchodilator reversibility and no patterns indicating obstruction or restriction.