Asthma Diagnosis, Classification and Its Complications

Diagnosis of asthma can be done by taking a thorough medical history and performing breathing tests to measure how well your lungs work.

November 24, 2017

Diagnosis of asthma can be done by taking a thorough medical history and performing breathing tests to measure how well your lungs work.

Physical Examination:

Your doctor will do a physical exam and ask you questions about your signs and symptoms and about any other health problems to rule out other possible conditions such as a respiratory infection or chronic obstructive pulmonary disease (COPD).

Lung Function Test:

Lung or pulmonary function tests can be done to determine how much air moves in and out as you breathe. These tests may include:


This test is done to determine the narrowing of your bronchial tubes by checking how much air you can exhale after a deep breath and how fast you can breathe out.

Peak flow:

A peak flow meter is a simple device that measures how hard you can breathe out. If the peak flow readings are lower than usual, your lungs may not be working properly and your asthma may be getting worse.
Usually lung function tests are done before and after taking a medication called a bronchodilator such as albuterol, to open your airways. If your lung function improves with use of a bronchodilator, it is likely that you have asthma.

Other Test:

Methacholine challenge:

Methacholine is a asthma trigger that will cause mild constriction of your airways, when inhaled . If you react to the methacholine, you are likely to have asthma. Even if your initial lung function test is normal, this test should be done.

Nitric oxide test:

When your airways are inflamed, you may have higher than normal nitric oxide levels in your breath which can be measured by this test.

Allergy testing:

This can be performed by a skin test or blood test which will identify allergy to pets, dust, mold and pollen.

Sputum eosinophils:

While you cough, the discharge which is a mixture of saliva and mucus (sputum) will have certain white blood cells (eosinophils). Eosinophils are present when symptoms develop and become visible when stained with a rose-colored dye (eosin).

Imaging tests:

Any structural abnormalities or diseases such as infection that can cause or aggravate breathing problems can be identified by a chest X-ray and high-resolution computerized tomography (CT) scan of your lungs and sinuses.

Provocative testing for exercise and cold-induced asthma:

Your airway obstruction can be measured before and after you perform vigorous physical activity or take several breaths of cold air.

Classification of Asthma:

Asthma is classified into four general categories depending on the severity, signs and symptoms.

Mild intermittent:

It will have mild symptoms up to two days a week and up to two nights a month.

Mild persistent:

Symptoms will occur more than twice a week, but no more than once in a single day.

Moderate persistent:

In this case you will have symptoms once a day and more than one night a week.

Severe persistent:

Symptoms occur throughout the day on most days and frequently at night.

Complications of Asthma:

Asthma complications include:

  • Signs and symptoms that interfere with sleep, work or recreational activities
  • Permanent narrowing of the bronchial tubes that affects how well you can breathe
  • Hospitalizations for severe asthma attacks
  • Side effects from long-term use of some medications used to stabilize severe asthma

Both short-term and long-term complications caused by asthma can be prevented by proper treatment.