Asthma Tests

There are some key asthma tests your doctor will use in diagnosing asthma. Some asthma tests, such as lung (or pulmonary) function tests, measure lung function. Other asthma tests determine if you are allergic to specific foods, pollen, or other particles. Blood tests give a picture of your overall health; specific tests also measure levels of immunoglobulin E (IgE), a key antibody that’s released during an allergic reaction. While everyone makes IgE, people who have allergies make larger quantities of this protective protein.

All of these asthma tests help your doctor determine if asthma is indeed present and if there are other coexisting conditions with asthma, such as allergies, GERD, or sinusitis. Once a proper asthma diagnosis is made, specific asthma medications can be prescribed to help manage your asthma and prevent asthma attacks.

Lung Function Tests

Lung function tests are asthma tests that assess lung function. The two most common lung function tests used to diagnose asthma are spirometry and methacholine challenge tests.

Spirometry is a simple breathing test that measures how much and how fast you can blow air out of your lungs. It is often used to determine the amount of airway obstruction you have. The methacholine challenge test may be performed if your symptoms and screening spirometry do not clearly or convincingly establish a diagnosis of asthma. Your doctor will know which test is best for your situation.

Chest X-Ray

While a chest X-ray is not an asthma test, it may be used to make sure nothing else is causing your asthma symptoms. An X-ray is an image of the body that is created by using low doses of radiation reflected on special film or a fluorescent screen. X-rays can be used to diagnose a wide range of conditions, from bronchitis to a broken bone. Your doctor may perform an X-ray exam on you in order to see the structures inside your chest, including the heart, lungs, and bones. By viewing your lungs, your doctor can see if asthma is causing your symptoms.

Evaluation for Heartburn and GERD

Gastroesophageal reflux disease, commonly called GERD, is another condition that may worsen asthma. If your doctor suspects this problem, he or she may recommend specific tests to look for it.

For more detail, see WebMD's article on Heartburn and Asthma.

Allergy Tests

Allergy testing may be recommended to identify any allergies that trigger asthma symptoms.

For more detail, see WebMD's article on Allergies and Asthma.

Evaluation of the Sinuses

The presence of nasal polyps or sinusitis may make asthma harder to treat and control. Sinusitis, also called sinus infection, is an inflammation or swelling of the sinuses due to infection. When the sinuses become blocked and filled with fluid, bacteria grow, causing infection and inflammation. Your doctor may order a special sinus X-ray, called a CT scan, to evaluate your sinuses if he suspects an infection. Once acute sinusitis is diagnosed, you will be treated with antibiotics for at least 10 to 12 days. Treating the sinusitis may help in preventing asthma symptoms.

For in-depth information, see WebMD's Sinusitis and Asthma.