How is asthma diagnosed?

Asthma is diagnosed not with a single blood test, but by evaluating the patient's history of symptoms together with respiratory tests. The doctor looks for two things: a symptom pattern specific to asthma and measurements that show variability in the narrowing of the airways.

What symptoms does the doctor ask about?

Wheezing, shortness of breath, chest tightness, and coughing are typical symptoms of asthma. In asthma, these symptoms are usually multiple, vary throughout the day and from day to day, and worsen at night or in the early morning. Exercise, laughter, cold air, allergens, cigarette smoke, and viral infections can trigger symptoms.

The doctor will also ask if there is a family history of asthma or allergies, or any accompanying conditions such as eczema or hay fever. Noting down when and where you experienced your symptoms will greatly facilitate the examination.

Spirometry: basic test

Spirometry is a painless test where you take a deep breath and blow into the device as quickly and forcefully as possible. The two most important measurements are:

• FEV1: Amount of air expelled in the first second.

• FVC: Total amount of air exhaled after a deep breath.

A low FEV1/FVC ratio indicates airway narrowing. A rescue medication (bronchodilator) is then administered, and the test is repeated after 10 to 15 minutes. A significant increase in FEV1, meaning the narrowing has improved with medication, strongly supports a diagnosis of asthma.

Even if the spirometry result is normal, it could still be asthma. If the test was done on a symptom-free day, the result may appear normal. Therefore, the doctor may repeat the test at different times.

Other tests that support the diagnosis

• Peak flow monitoring: Measurements are taken at home in the morning and evening for several weeks. Large fluctuations in values are indicative of asthma.

• FeNO test: Measures nitric oxide levels in the breath. High values suggest allergic inflammation in the airways.

• Bronchial provocation test: If the diagnosis is still uncertain, this is performed in a hospital setting to measure the sensitivity of the airways.

• Allergy tests: Skin tests or blood tests help identify allergens that trigger symptoms. They are not a diagnosis of asthma on their own.

• Chest X-ray: It doesn't show asthma, but it may be ordered to rule out other diseases that present with similar symptoms.

Diagnosis in young children

Children under five years of age generally cannot perform a spirometry test. In this age group, diagnosis is made by evaluating a combination of recurrent wheezing attacks, symptom patterns, family history of asthma, and response to short-term treatment trials. Not every child with wheezing has asthma; therefore, follow-up is important.

Why is it important to get tested before starting treatment?

Test results may return to normal after preventive medication is started, making it more difficult to confirm the diagnosis. Tests should be done before treatment if possible. However, if symptoms are severe, treatment should not be delayed.

Conclusion

Diagnosing asthma is a process. Keeping a record of your symptoms, regularly attending tests, and speaking openly with your doctor will help you reach an accurate diagnosis most quickly.

This article is for informational purposes only. For diagnosis and treatment, please consult a doctor.