Asthma and Lung Function Tests
Other Tests You May Need if You Have Asthma
Even if your lung function tests are normal, your doctor may order other tests to see what could be causing your asthma symptoms.
Allergy tests are used to pinpoint substances called allergens to which you might be allergic. Your doctor might do such tests by pricking your skin with a tiny amount of the allergen, by injecting it under your skin, or by giving you a blood test.
Gas and diffusion tests can measure how well your blood absorbs oxygen and other gases from the air you breathe. You breathe in a small amount of a gas, hold your breath, then blow out. The gas you exhale is analyzed to see how much your blood absorbed.
X-rays may tell if there are any other problems with your lungs or sinuses, or if asthma is causing your symptoms. High-energy radiation creates a picture of your lungs. You may be asked to briefly hold your breath while you stand in front of the X-ray machine.
In addition, you may need other tests to rule out other problems, such as sinus disease, gastroesophageal reflux disease (GERD), and heart problems.