Can asthma occur with normal spirometry?

The result is one part of the assessment. A clinician considers the symptom pattern, examination, test quality and whether airflow changes after medicine before deciding what the result means for you.

Spirometry measures how much air you can force out and how quickly you can do it. Asthma symptoms may come and go, so a test taken on a symptom-free day can fall within the expected range. Technique also matters: an incomplete breath in, an early stop or poor seal around the mouthpiece can affect the tracing.

A normal result makes persistent airflow obstruction less apparent at that visit, but it does not identify every cause of cough, wheeze or breathlessness. The clinician may also consider upper-airway problems, reflux, infection, heart conditions or other lung disorders according to the history.

Record when symptoms occur, possible triggers, night waking and how exercise affects breathing. Bring details of current inhalers and whether they change symptoms. The clinician may repeat spirometry when symptoms are present, check response to a bronchodilator or choose another airway test when appropriate.

Do not stop prescribed preventer treatment solely because one test was normal. Changing medication before a planned test can alter the findings, so follow the preparation instructions provided by the testing service.

Seek emergency help for severe or rapidly worsening breathlessness, inability to speak comfortably, blue or grey lips, confusion, collapse, or poor response to your prescribed reliever. A previous normal spirometry result should never delay urgent assessment of current breathing difficulty.

Arrange a timely review if cough, wheeze or chest tightness keeps returning, wakes you from sleep, limits activity or requires reliever medicine more often than your action plan allows.

Ask whether the test met quality standards, whether your results changed after bronchodilator medicine and whether repeat or alternative testing is suitable. Clarify which medicines to continue before future testing and what symptoms should trigger an earlier appointment.