Lung function tests are tests that help doctors diagnose asthma, states WebMD. Also called pulmonary function tests, these tests include a number of procedures to diagnose breathing problems. Spirometry and the methacholine challenge test are the two most common lung function tests.
When a patient has breathing problems and the doctor suspects asthma, lung function tests are part of the process of diagnosing – or ruling out – asthma. Spirometry measures the amount of air the patient can blow out of the lungs and how quickly; this test can determine the extent of the patient’s airway obstruction. The methacholine challenge test involves giving the patient an agent to inhale that causes the airways to spasm if asthma is present, according to WebMD.
Patients with breathing problems can also expect their doctors to consider their medical histories and current symptoms, so patients should be prepared to describe their symptoms in detail, including when symptoms occur, how often and what the symptoms are, for example, coughing, chest tightness, wheezing or shortness of breath. The doctor will also typically perform a physical exam and listen to the patient’s heart and lungs. WebMD says that besides lung function tests, the doctor may also want to perform allergy tests, chest X-rays, or other tests to help reach a correct diagnosis.