There is no single test for asthma. Your doctor will decide if you have asthma based on talking to you, examining you and performing some breathing tests.
A diagnosis of asthma is more likely if you have eczema or hayfever or have close relatives with allergies and/or asthma, and if your symptoms:
- keep coming back, or happen at the same time each year
- are worse at night or in the early morning
- are clearly triggered by exercise, allergies or infections
- improve quickly with reliever medication
It’s often difficult to diagnose asthma in young children, especially as they can’t do the breathing tests. The doctor will assess the symptoms and history and may give asthma medicine to see what effect it has, so it can take some time to come to a diagnosis. Your doctor should get you to perform a spirometry test.
A spirometry test measures how well your lungs are working, and whether something (such as your asthma) is affecting your breathing. You might do the test in the doctor’s room, or sometimes you’ll need to go to an other clinic or hospital to have the test done. It depends on where the equipment is available.
A spirometry test is safe, simple and painless. It involves blowing as hard as you can, for as long as you can, into a tube or mouthpiece which is connected to a special measuring machine. You’ll need to do this several times, but you can rest as long as you need to in between. Sometimes you’ll need to take a few puffs of an asthma reliever medication, wait a few minutes, and then do the test again. This will show what effect the medication has on your lungs.
Spirometry tests are not usually performed on children younger than 6 years old.
Some people might also have to do a challenge test.
In this test you have to inhale a special substance and then do a spirometry test. The reaction your lungs have to the substance shows if you have sensitive airways and can help decide the best treatment for you. This test is usually done in hospitals or respiratory function laboratories.
Asthma is strongly linked with allergies, and so many people may have allergy tests – usually skin prick tests or blood (RAST) tests. These tests detect which allergens you are sensitive to. Skin prick testing is usually done on the forearm. A drop of allergen is put on the skin and a small prick into the skin is made through the drop to allow a tiny amount of allergen to enter. If you are allergic, a small lump will appear in the next 15 to 20 minutes. Blood (RAST) testing may be performed if skin testing is not possible, such as in cases of severe eczema. This test involves taking a sample of blood which is checked for antibodies to specific allergens.
Tests you don’t need
A chest x-ray is not generally helpful in diagnosing or monitoring asthma, but you might have one if your doctor wants to rule out other problems such as pneumonia. There are several other methods that claim to test for allergy. These include kinesiology, Vega testing, hair analysis and many others. Many of these are not scientifically validated and are not recommended.
What else could it be?
There are a number of other things besides asthma that might need to be considered. Click here to get more information about these alternatives.