Diagnosing asthma: the first step to know if you have asthma is to visit your doctor to assess your general condition. During the consultation, you may be asked about the symptoms you have experienced, as well as for how long and how often they appear. It is very important that the diagnosis of asthma or any other disease is made by your doctor prior to any treatment.
For a correct diagnosis of asthma, the doctor will take into account the following:
- Review of your medical history, including your family history related to respiratory conditions.
- A physical exam that may include a review of your ears, eyes, nose, throat, chest and upper respiratory tract.
- In addition, they may ask you to do various tests to determine your lung function.
Among the pulmonary function tests, the most common and reliable for the diagnosis of asthma is “Spirometry”. This consists of measuring the amount of air you can inhale and exhale, as well as the maximum air flow. That is, the speed with which you expel the air from the lungs. If your doctor deems it necessary, you can perform additional tests. Such as immunoglobulin E (IgE) analysis, sensitivity of the airways, or chest x-ray. (Diagnosing Asthma)
Diagnosing Asthma: Tests
How to diagnose asthma?
To make the diagnosis of asthma, the doctor observes the symptoms that indicate that there is an obstruction in the airways. For example, you may hear wheezing and other sounds as a result of narrowing of the airways.
To confirm the diagnosis, you can order tests that help determine lung function, such as spirometry. This test can also be done with bronchodilator drugs that work by decreasing the obstruction. They are the bronchodilation tests. But also, with drugs that reveal bronchial obstruction, and are provocation tests.
Otra alternativa, es medir la fracción exhalada de óxido nítrico (FENO), que demuestran que los bronquios están inflamados y la respuesta a algunos tratamientos.
It is also convenient to do a chest x-ray, to rule out other possible diseases. In case of a more serious crisis, the professional can request an arterial blood gas.
In those cases where the cause of asthma may be exposure to a substance, it would be advisable to do allergy tests.
- Pulmonary function tests (PFTs).
- Spirometry: measures how much air the lungs are able to breathe in and how much air they breathe out and how fast a person can exhale.
- Broncho-provocation test: In this test, the airways (bronchi and bronchioles) are caused to have a bronchospasm (constricts the airways). So to see how sensitive they are. For example, to provoke bronchospasm, the patient is put to exercise. As well as breathing cold air or inhaling a special chemical called methacholine. The results of bronchoprovocation are checked using spirometry. (Diagnosing Asthma)
Diagnosing Asthma – Common symptoms and signs of asthma include:
- Breathing difficulty
- Tightness in the chest
- Worsening symptoms at night
- Worsening symptoms due to cold air
- Symptoms while exercising
- Symptoms after exposure to allergens
It is also wise to make note of health conditions that can interfere with asthma management such. As, runny nose, sinus infections, acid reflux disease, psychological stress, and sleep apnea.
It is often a little more difficult to diagnose young children who may develop their first asthma symptoms before age 5. Thus, asthma symptoms can lead to confusion with other childhood conditions. But young children with episodes of wheezing during colds or respiratory infections can develop asthma after 6 years of age.
Diagnosing Asthma: Physical Exam
- A physical examination will generally focus on the upper respiratory tract, chest, and skin. A doctor will use a stethoscope to listen for signs of asthma in your lungs as you breathe. The high-pitched whistling sound while you exhale – or wheezing – is a key sign of both an obstructed airway and asthma.
- Physicians will also check for a runny nose, swollen nasal passages, and nasal polyps. Skin will be examined for conditions such as eczema and hives, which have been linked to asthma.
- Physical symptoms are not always present in those with asthma. It is possible to have asthma without presenting physical illnesses during an exam. (Diagnosing Asthma)
See also: “Asthma Treatment“
- Lung function tests, or pulmonary function tests, are the third component of an asthma diagnosis. To measure how much air you breathe in and out and how fast you can blow air out, physicians administer a spirometry test.
- Spirometry is a noninvasive test. That requires you to take deep breaths and forcefully exhale into a hose connected to a machine called a spirometer. The spirometer then displays two key measurements:
- Forced vital capacity (FVC) – the maximum amount of air one can inhale and exhale.
- Forced expiratory volume (FEV-1) – the maximum amount of air exhaled in one second.
- The measurements are compared against standards developed for a person’s age, and measurements below normal may indicate obstructed airways.
- It is common for a doctor to administer a bronchodilator drug to open air passages before retesting with the spirometer. If results improve after the drug, there is a higher likelihood of receiving an asthma diagnosis.
- Children under the age of 5 are difficult to assess using spirometry. Therefore, asthma diagnoses will depend primarily on symptoms, medical history, and physical examination. It is common for doctors to prescribe asthma medications for 4 to 6 weeks. To see how a small child responds.
Other Tests (Diagnosing Asthma)
- A broncho-provocation test is when a doctor administers a substance that constricts the airways. Similarly, it uses cold air, to cause an obstruction of the airways and achieve asthma symptoms.
Similarly, a test to induce asthma through exercise would consist of vigorous exercise to trigger symptoms. Then a spirometry test is administered, and if the measurements are still normal, a diagnosis of asthma is unlikely.
- Physicians use allergy tests to identify substances that may be causing or worsening asthma. These tests cannot be used to diagnose asthma, but they can be used to understand the nature of asthma symptoms.
Doctors may also test for another disease with similar symptoms as asthma. Such as:
- Reflux disease
- Hay fever
- Sleep apnea
- Chronic obstructive pulmonary disease (COPD)
- Airway tumors
- Airway obstruction
- Lung infection (pneumonia)
- Blood clot in the lung (pulmonary embolism)
- Congestive heart failure
- Vocal cord dysfunction
- Viral lower respiratory tract infection.
There are other tests for these ailments, such as:
- Chest x-rays
- EKGs (electrocardiograms)
- Complete blood counts
- CT (computerized tomography) scans of the lungs
- Gastroesophageal reflux assessment, and sputum induction and examination.
- A new test with exhaled nitric oxide is being evaluated. Since doctors are looking for a test that is more accurate than spirometry. Higher levels of nitric oxide are related to higher degrees of asthma severity. The current drawback lies in the high cost of the test and the specialized equipment required to measure this chemical marker.
- An asthma specialist can usually be avoided, since most primary care physicians are able to diagnose asthma. However, an asthma specialist may be necessary if you need special asthma tests. Especially if you have had a life-threatening asthma attack in the past. Also, specialists can be helpful if you need more than one type of medication. Also, if you require higher doses of medications to control your asthma. Or in case of general difficulties in controlling asthma. As well as, if you will receive allergy treatments.