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Your doctor may diagnose you with asthma based upon your signs and symptoms and after performing a physical exam and certain tests.
The diagnosis of asthma is done by a doctor based upon your signs and symptoms, relevant medical history, physical examination, and certain tests.
The typical symptoms of asthma include:
- Shortness of breath
- Chest tightness or pressure (feeling as if a tight band is around the chest)
- Coughing (cough variant asthma)
- Wheezing (a whistling or rattling sound while breathing typically on exhaling)
These symptoms may cause disturbance in sleep or taking rest.
- Asthma symptoms may be worsened by infection such as cold or flu.
- Some people may report worsening symptoms during exercise and being exposed to cold, pollen, or environmental irritants such as fumes or smoke. One distinctive feature of exercise-induced asthma is that the symptoms develop about 5 to 15 minutes after starting physical activity and not immediately. The symptoms may take about 30 minutes to an hour to go away after rest.
Asthma symptoms are typically intermittent or episodic. This means that the symptoms generally come and go away. Patients may report their symptoms getting worse at night.
While the above symptoms are generally seen in asthma, you must consult your doctor for a definitive diagnosis. This is because these symptoms may be seen in other lung or heart conditions.
Contact your doctor immediately if:
- You have severe shortness of breath on doing even mild activity or while at rest.
- Your lips or skin appear bluish.
- Your symptoms interfere with sleep or taking rest.
- You get severe chest pain.
- You feel dizzy or irritable.
- You get a fever.
What are the tests for the diagnosis of asthma?
Your doctor may ask about your detailed medical history along with any history of asthma in your family. They may also ask about your occupation, any underlying health conditions, medications that you may be taking, and what worsens your symptoms.
Doctors generally perform a detailed physical examination, especially a chest examination, to check your breathing and heart sounds. They may also examine your nose and skin to look for any signs of inflammation or allergies. They may then order certain tests to confirm their diagnosis and rule out other health conditions and plan proper treatment.
While there is no particular test to diagnose asthma, some of the investigations that may be done include:
- Pulmonary function tests (PFT): These tests measure how well your lungs are functioning.
- Spirometry: PFT is generally done by spirometry, which is a technique that involves using a device called a spirometer. It has a mouthpiece attached to a machine that gives information about airflow through your lungs when you blow into the mouthpiece.
- Peak expiratory flow: An important parameter measured in PFT is called peak expiratory flow. It measures your capacity to push out air from your lungs. The peak expiratory flow can be measured by using a portable and inexpensive device called a peak flow meter.
- Bronchodilator response: It measures the improvement in your lung function in response to a type of medication called a bronchodilator. Bronchodilators help open the airways. If there is improvement in airflow through the lungs in response to bronchodilators, it means that you have asthma.
- Bronchoprovocative testing: This test involves inducing mild narrowing of airways (bronchoconstriction) using certain drugs. This helps diagnose asthma in people who have nonconclusive baseline tests. Bronchoconstriction may be induced by giving certain drugs (such as inhaled methacholine or mannitol), exercise, or breathing in the presence of dry air.
- Nitric oxide in exhaled air: This test measures the levels of the gas called nitric oxide in patients' breath when they exhale. Asthma causes increased activity of an enzyme called nitric oxide synthase that increases nitric oxide levels in the exhaled air of asthma.
- Imaging tests: A chest X-ray (also called a radiograph) may be done to visualize the lungs. A special type of computed tomography (CT) scan, called high-resolution CT or HRCT, may also be done to further confirm the diagnosis and find out if asthma has led to any chronic changes in the lungs.
- Blood tests: Blood tests such as blood counts, alpha-1-antitrypsin levels (reduced in a lung condition called emphysema), and blood sugar levels may be done to reach a diagnosis and plan proper treatment.
- Allergy testing: Certain blood or skin tests may be done to look for allergies that may be causing the symptoms. A raised level of a type of antibody called IgE (immunoglobulin E) may indicate allergies. Knowing the allergens may help know and thus avoid what triggers the symptoms.
- Sputum test: Sputum or the mucus coughed out of the airways may also help in diagnosis. Sputum may be analyzed for eosinophils, which are a special type of white blood cells that are raised in allergic conditions. Sputum may also be analyzed for ruling out infections (such as tuberculosis).
What causes asthma?
Asthma is a chronic condition that causes tightness and narrowing of the airways. This hampers breathing causing symptoms such as shortness of breath, coughing, and wheezing.
The exact cause of asthma is not known; however, certain conditions may increase your risk, such as:
- Genetics: Having a first-degree relative (such as a parent or sibling) with asthma may increase your likelihood of having asthma.
- Infections: Certain respiratory infections in early life may increase the asthma risk.
- Allergies: People with certain allergies may be more likely to get asthma.
- Environmental pollutants: Exposure to certain chemicals or irritants may cause or trigger asthma.
Certain factors may trigger an asthma attack in susceptible individuals. Knowing and avoiding these triggers may help prevent asthma flare-ups. These triggers may include:
- Physical activity or exercise
- Allergens such as pollen, dust, mites, pet dander, or molds
- Cold, dry air
- Certain infections such as flu or cold
- Environmental pollutants such as smoke or car exhaust
- Stress
- Certain medications such as aspirin, beta-blockers, and nonsteroidal anti-inflammatory drugs
- Acid reflux or heartburn
- Certain food or wine additives such as sulfites
- Hormonal changes such as menstrual periods