Asthma: Tests and Diagnosis 

Asthma: Tests and Diagnosis 

Asthma, a chronic respiratory disease, causes inflammation and narrowing of the airways thereby affecting your breathing. This long-term lung disease is characterized by shortness of breath, coughing, wheezing, and chest tightness.

There is no one single cause of asthma as researchers believe the disease is caused by various factors that include;

  • Allergies. Frequent exposure to possible irritants and allergens may irritate the airways
  • Genetics
  • History of viral disease

Other triggers may include;

  • Respiratory illness like pneumonia and flu
  • Extreme weather conditions
  • Exercise

Asthma Classification

Doctors rank asthma based on their symptoms;

  • Mild asthma. It can be either intermittent or persistent. Intermittent asthma is characterized by mild symptoms twice a week, fewer asthma attacks and nighttime symptoms occurring less than twice a month.
  • Persistent asthma, the symptoms occur three to six times a week and nighttime symptoms three to four times a month. You will have frequent asthma attacks.
  • Moderate asthma is when the symptoms occur three to six times a week
  • Severe asthma has ongoing symptoms experienced both day and night and it affects and limits your activities.

So how does the doctor determine the severity? Using asthma pulmonary function test for asthma.

What is Lung Function Tests?

To diagnose and classify asthma, our doctor reviews your asthma symptoms, family and medical history. Additionally, they also do a pulmonary function test to determine your breathing patterns.

Several lung function test are available and they include;


This is an asthma breathing test that measures how much air you inhale and how quickly you exhale.

Spirometry reveals the amount of obstruction you have in your airways. To perform this test, you will take a deep breath and blow it out as hard and quickly as you can into a hose attached to the spirometer. This process is repeated three times for consistency.

Spirometer uses two measurements;

FVC (Forced Vital Capacity) which measures how much air you inhale and exhale

FEV (Forced Expiratory Volume) which indicates how much air you can breathe out from your lung in one second.

  • Preparation for the spirometry test
  • Avoid heavy meals before the test
  • Wear comfortable clothes
  • Confirm with your doctor if there are medications to be avoided before the test
  • Peak Flow Meter Test

Using the peak flow meter, the doctor will measure the maximum speed at which your lung blows air out. The test will show how narrow the airways have become.

Although peak flow meter is not as effective as a spirometer, it is a good way to test your lung function at home. The meter is ideal for people above seven years.

  • FeNo test

FeNo or exhaled nitric oxide test is done to determine how much inflammation you have on your airways and is done on people with eosinophilic or allergic asthma.

Provocation or challenge test

There are three types:

  • Exercise test that shows if you have exercise-induced bronchoconstriction (meaning exercise is a trigger for your asthma). The doctor watches the oxygen and heart rate as you are using a treadmill.
  • Methacholine test is done in conjunction with spirometry. You will inhale methacholine mist before and after the spirometry test. Don’t worry you will get medication at the end of the test to reverse methacholine effects.
  • Irritant test. The doctor will expose you to a trigger like chemicals, smoke, or perfume, then do a breathing test to see how well the lungs respond.

How to Prepare for the Lung Function test

Ask your doctor if there’s anything you need to do before the test. Additionally, inform them if you have any viral infections or flu shots.

  • Don’t smoke
  • Avoid exercise
  • Don’t have coffee, tea, chocolate, or cola

Also, you might be required to adjust some of the asthma drugs that are taking as certain medications can affect your test results. So, discuss with the doctor if you need to stop any drugs.

Living with Asthma

Currently, there’s no cure for asthma, but various treatment options are available that can help reduce the symptoms. The key to living with asthma is to be educated.

  • Know the type of asthma you have and the lung function test will help you with that
  • What are the triggers and which treatments are ideal for you?