When diagnosing asthma, the doctor is likely to rely on the results of asthma testing. Different tests are used to measure the inflammation of the airways of someone who is experiencing asthma symptoms. During the initial consultation, the doctor will ask about the symptoms of asthma. If the doctor suspects that asthma is the cause of these symptoms, the doctor may order asthma testing.

The pulmonary function test, also called the lung function test or spirometry, is a common test for checking the inflammation of the airways. During a pulmonary function test, the person is required to exhale rapidly through a tube. The airflow is measured by a computer connected to the breathing apparatus. The test can measure the amount of the person’s impairment of lung function.

A methacholine test is similar to a pulmonary function test except that methacholine is inhaled during the test. Methacholine is a drug that will cause airway constriction in someone with asthma. The person is likely to be asked to perform some breathing exercises first, which are measured. After the person inhales methacholine, the person must repeat the breathing exercises. If the individual’s breathing has been impaired by at least twenty percent, the person is likely to have asthma. After the test, a bronchodilator, like albuterol, is given to the patient to reverse the effects of the methacholine.

A peak flow test measures the fastest speed that the person can forcefully, yet steadily exhale. Once people know their peak flow, they can retake the test at a later time and check for impaired lung function. If they cannot achieve their peak flow, there may be airway constriction or inflammation interfering with the individual’s airflow. A peak flow meter may be given to the patient to help them monitor their lung functioning at home. If a patient uses a peak flow meter when the patient thinks that an asthma attack may be eminent, it can show whether or not there is inflammation or constriction.

Occasionally, a doctor may order a chest x-ray to rule out other causes of inhibited breathing. A chest x-ray can rule out pneumonia or other conditions that can be mistaken for asthma. A blood test may be done to rule out infections as causing the symptoms. Once the doctor has the results from the asthma testing, the doctor can diagnose or rule out asthma. If the patient is diagnosed with asthma, the next step is to find the best treatment plan for the asthma patient.