Diagnosis of Asthma

Initial Visit

The initial visit with the doctor involve determining whether the patient has asthma or some other condition that may be causing similar symptoms. Diagnosis of asthma will usually involve a thorough medical and physical examination as well as tests.

Medical History for Asthma Diagnosis:

Initially, a thorough medical history will be conducted. The doctor may want to know of any allergies the patient has as well as any history of asthma or allergies in any blood relatives. The doctor will also want to know the frequency and severity of symptoms such as coughing, wheezing, breathing difficulty and chest tightness. It is also important to provide information such as whether there is any pattern to when the symptoms occur i.e. after exercising or playing with a particular animal. Other things to mention are whether symptoms become worse at any particular time i.e. at night, when the air is cold or particular yearly seasons.

The health professional may ask questions regarding the history of symptoms such as coughing and recurrent wheezing, chest tightness and breathing difficulty. They may also ask questions about whether the symptoms are worse at night or appear to be triggered by such things as stress, exposure to allergens or irritants, viral infections, exercise, weather changes or laughing or crying hard. Other questions from the doctor are:

  • whether symptoms develop rapidly
  • how often exacerbation of symptoms occurs
  • whether the symptoms escalated to a point where hospitalization was required
  • how many days of school or work were missed
  • whether any activities are limited because of the symptoms.

Physical Examination for Asthma Diagnosis:

A physical examination can involve the doctor using a stethoscope to listen to the lungs during breathing in order to listen for signs of asthma such as wheezing. The doctor may also check for nasal polyps, nasal passage swelling or a runny nose. The skin may be examined to look for the presence of allergic skin conditions such as eczema or hives, which have been linked to the presence of asthma.

Diagnosing Asthma in Young Children:

Many children develop asthma within the first few years of life. At this age, it can be difficult to determine if they have asthma or not as they are unable to verbally describe their symptoms and the majority of the tests are difficult to perform on young children. Just because a young child often becomes wheezy when they have a cold, it does not mean they have asthma. Their airways tend to be much smaller than an adult so are less tolerant to the effects of colds and flu.

Due to the difficult of performing tests on young children, the doctor will usually rely on a medical history, observed signs or symptoms and a physical examination to make a diagnosis. The doctor may recommend trialling asthma medication to see if this helps to resolve the symptoms. If medication results in an improvement in symptoms then it is more likely that asthma is a correct diagnosis though further monitoring is required as an underlying cause of the symptoms may have resolved and caused the symptoms to improve.

Once the patient has been diagnosed as having asthma, the next step is to determine the severity of the condition. The severity is assessed by noting how often a patient develops symptoms, how much it impacts on their normal activity, how often symptoms escalate. There are a number of possible tests the doctor may conduct.


Spirometry Test

  • The most frequently used test is spirometry. This is a non-invasive test where the patient takes a deep breath and blows into a sensor, which allow the measurement of the amount of air in the lungs as well as the speed of the air, which is inhaled or exhaled. Sometimes the doctor will repeat the test after administering a bronchodilator (a drug which opens up the airways). If the results improve after the drug administration, then the likelihood of having asthma is higher.

Nitric Oxide Test

  • The nitric oxide test involves analysing the quantity of nitric oxide that is exhaled. Higher levels of exhaled nitric acid tend to be associated with increased asthma severity. The drawback of this test is the cost involved and the specialized equipment required.

Chest X-Ray or CT Scan

Metacholine Test

  • Methacholine is a known asthma trigger that causes minor narrowing of the airways when it is breathed in. As such, it is a useful asthma test as a reaction to methacholine means there is a definite likelihood that you have asthma.

Challenge Test for Exercise- or Cold-Induced Asthma

  • To assess for exercise or cold-induced asthma, the doctor may measure your lung function before and after performing a strenuous physical activity or before and after breathing in cold air.

Allergy Test

  • Your doctor may also recommend an allergy test to see if any allergies play a role in your asthma symptoms.

Asthma severity can be classified as intermittent, mild, moderate or severe.

When the doctor has decided on how severe the asthma is, he will provide a treatment plan, which will usually involve medication.

Once an asthma diagnosis has been made, a treatment plan will be initiated. This will usually involve the use of medication in the form of an inhaler. An asthma action plan will also need to be developed so the patient knows exactly what to do if symptoms get worse.

Follow-up Visit

You will need to return to the doctor for follow-up visits. During these visits the doctor will assess how well you are able to control you symptoms with the treatment plan you have been given. He will also review your medication technique, assess any side effects that you may have developed and establish whether you are adhering to the treatment plan. Depending on the outcome of the review, the doctor may decide to leave the treatment as is, reduce or increase the medication, or change the type of medication altogether. The doctor should also review the asthma action plan and revise as needed.

A follow-up care schedule usually involves returning to the doctor after two to six weeks while gaining control of the condition. Once the therapy appears to be adequately controlling the asthma, one to six monthly visits may be warranted to monitor the level of control.

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Back to: « Asthma

Diagnosis of Asthma

How Is Asthma Diagnosed?

Your primary care doctor will diagnose asthma based on your medical and family histories, a physical exam, and test results.

Your doctor also will figure out the severity of your asthma—that is, whether it's intermittent, mild, moderate, or severe. The level of severity will determine what treatment you'll start on.

You may need to see an asthma specialist if:

  • You need special tests to help diagnose asthma
  • You've had a life-threatening asthma attack
  • You need more than one kind of medicine or higher doses of medicine to control your asthma, or if you have overall problems getting your asthma well controlled
  • You're thinking about getting allergy treatments

Medical and Family Histories

Your doctor may ask about your family history of asthma and allergies. He or she also may ask whether you have asthma symptoms and when and how often they occur.

Let your doctor know whether your symptoms seem to happen only during certain times of the year or in certain places, or if they get worse at night.

Your doctor also may want to know what factors seem to trigger your symptoms or worsen them. For more information about possible asthma triggers, go to "What Are the Signs and Symptoms of Asthma?"

Your doctor may ask you about related health conditions that can interfere with asthma management. These conditions include a runny nose, sinus infections, reflux disease, psychological stress, and sleep apnea.

Physical Exam

Your doctor will listen to your breathing and look for signs of asthma or allergies. These signs include wheezing, a runny nose or swollen nasal passages, and allergic skin conditions (such as eczema).

Keep in mind that you can still have asthma even if you don't have these signs on the day that your doctor examines you.

Diagnostic Tests

Lung Function Test

Your doctor will use a test called spirometry (spi-ROM-eh-tre) to check how your lungs are working. This test measures how much air you can breathe in and out. It also measures how fast you can blow air out.

Your doctor also may give you medicine and then test you again to see whether the results have improved.

If the starting results are lower than normal and improve with the medicine, and if your medical history shows a pattern of asthma symptoms, your diagnosis will likely be asthma.

Other Tests

Your doctor may recommend other tests if he or she needs more information to make a diagnosis. Other tests may include:

  • Allergy testing to find out which allergens affect you, if any.
  • A test to measure how sensitive your airways are. This is called a bronchoprovocation (brong-KO-prav-eh-KA-shun) test. Using spirometry, this test repeatedly measures your lung function during physical activity or after you receive increasing doses of cold air or a special chemical to breathe in.
  • A test to show whether you have another condition with the same symptoms as asthma, such as reflux disease, vocal cord dysfunction, or sleep apnea.
  • A chest x ray or an EKG (electrocardiogram). These tests will help find out whether a foreign object or other disease may be causing your symptoms.

Diagnosing Asthma in Young Children

Most children who have asthma develop their first symptoms before 5 years of age. However, asthma in young children (aged 0 to 5 years) can be hard to diagnose.

Sometimes it's hard to tell whether a child has asthma or another childhood condition. This is because the symptoms of asthma also occur with other conditions.

Also, many young children who wheeze when they get colds or respiratory infections don't go on to have asthma after they're 6 years old.

A child may wheeze because he or she has small airways that become even narrower during colds or respiratory infections. The airways grow as the child grows older, so wheezing no longer occurs when the child gets colds.

A young child who has frequent wheezing with colds or respiratory infections is more likely to have asthma if:

The most certain way to diagnose asthma is with a lung function test, a medical history, and a physical exam. However, it's hard to do lung function tests in children younger than 5 years. Thus, doctors must rely on children's medical histories, signs and symptoms, and physical exams to make a diagnosis.

Doctors also may use a 4-6 week trial of asthma medicines to see how well a child responds.

Source: NHLBI (NIH)1

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A doctor will test for asthma by doing a physical exam and asking about your medical history to learn when and how often your symptoms occur. Your doctor may also ask you to breathe in and blow out into the tube of a spirometer. This device measures how much air you can breathe out and how fast you can do it.

“It’s sometimes tough to do a spirometry test on young children,” says Dr. Michelle Freemer, an NIH asthma expert. For youngsters, a doctor will do a physical exam and may perform other tests to identify possible asthma triggers.

Source: NIH News in Health (NIH)2

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Medical testing typically reveals evidence of bronchial hyperresponsiveness such as an abnormal methacholine challenge test or reversible airways obstruction on spirometry (a test of lung function).

Source: CDC NIOSH3

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Having these symptoms doesn't always mean that you have asthma. Your doctor will diagnose asthma based on lung function tests, your medical history, and a physical exam. You may also have allergy tests.

Source: MedLinePlus (NIH)4

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Not everyone with asthma has these symptoms. Nor does having them always mean asthma. To diagnose asthma for certain requires a lung function test, a medical history (including type and frequency of symptoms), and a physical exam.

Source: MedLinePlus Magazine (NIH)5

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When to see a GP

See your GP if you think you or your child may have asthma.

Several conditions can cause similar symptoms, so it's important to get a proper diagnosis and correct treatment.

Your GP will usually be able to diagnose asthma by asking about symptoms and carrying out some simple tests.

Read more about how asthma is diagnosed.

Source: NHS Choices UK6

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Asthma can usually be diagnosed from your symptoms and some simple tests.

Your GP will probably be able to diagnose it, but they may refer you to a specialist if they're not sure.

Seeing your GP

Your GP may ask:

  • what symptoms you have
  • when they happen and how often
  • if anything seems to trigger them
  • if you have conditions such as eczema or allergies, or a family history of them

They may suggest doing some tests to confirm if you have asthma.

These can't always be done easily in young children, so your child may be given an asthma inhaler to see if it helps relieve their symptoms until they're old enough to have the tests.

Source: NHS Choices UK7

Tests for Asthma

Tests for asthma

The main tests used to help diagnose asthma are:

  • FeNO test - you breathe into a machine that measures the level of nitric oxide in your breath, which is a sign of inflammation in your lungs
  • spirometry - you blow into a machine that measures how fast you can breathe out and how much air you can hold in your lungs
  • peak flow test - you blow into a handheld device that measures how fast you can breathe out, and this may be done several times over a few weeks to see if it changes over time

After you're diagnosed with asthma, you may also have allergy tests to see if your symptoms might be triggered by an allergy.

Asthma UK has more information on diagnosing asthma.

Source: NHS Choices UK8

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  1. Source: NHLBI (NIH): nhlbi.nih.gov/ health/ health-topics/ topics/ asthma/ diagnosis
  2. Source: NIH News in Health (NIH): newsinhealth.nih.gov/ issue/ jun2014/ feature1
  3. Source: CDC NIOSH: cdc.gov/ niosh/ topics/ indoorenv/ moldsymptoms.html
  4. Source: MedLinePlus (NIH): medlineplus.gov/ asthma.html
  5. Source: MedLinePlus Magazine (NIH): medlineplus.gov/ magazine/ issues/ fall13/ articles/ fall13pg12-13.html
  6. Source: NHS Choices UK: nhs.uk/ conditions/ Asthma/ 
  7. Source: NHS Choices UK: nhs.uk/ conditions/ asthma/ diagnosis/ 
  8. ibid.

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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.