Your doctor may use several tests to make an asthma diagnosis, including lung function tests. The most likely lung function test will measure how much air you can exhale. These important asthma tests confirm the presence of airway obstruction that improves with asthma treatment.
As an example, your doctor will have you perform spirometry, a lung function test that measures how much air you can blow out of your lungs and how quickly. This asthma test is done before and after using an asthma inhaler with albuterol, a bronchodilator. If your airways expand, allowing air to pass through more freely, then it is highly likely that asthma is the cause of your respiratory symptoms.