Tests to diagnose and monitor asthma in young children

Diagnosis of asthma in children under age 5 can be challenging. The primary symptoms may indicate other conditions. With older children a doctor can use a breathing test that measures how well the lungs work, but these tests are not useful with younger children, who may have trouble following instructions and breathing exactly as directed.

If your child under age 5 has symptoms that might indicate asthma, your doctor or asthma specialist will likely use several pieces of information to make a diagnosis.

Medical history

Your doctor will likely ask a number of questions, such as the following:

• Is there a family history of asthma?
• How often do symptoms occur?
• Does coughing wake your child at night?
• Do the symptoms accompany a cold or are they unrelated to colds?
• How often do episodes of breathing difficulty occur?
• How long do they last?
• Has your child needed emergency care for breathing difficulties?
• Does your child have any known pollen, dust, pet or food allergies?
• Is your child exposed to cigarette smoke or other airborne irritants?

Laboratory tests

Other tests may include the following:

• Blood test. Your doctor can measure the levels of certain white blood cells that may be elevated in response to infections.
• Chest X-ray. A chest X-ray may reveal changes in the lung when asthma is moderate to severe. It may also be used to rule out other conditions.
• Allergy test. A skin or a blood test may indicate if your child is allergic to a suspected or likely allergen.

Trial treatment

If your doctor suspects your child has asthma, he or she will likely prescribe a trial treatment. If your child has relatively mild and infrequent symptoms, he or she may take a short-acting drug. If breathing improves in the time and manner expected for that treatment, the improved breathing would support a diagnosis of asthma.

If the symptoms are more regular or severe, your doctor will likely begin a drug for long-term management. Improvement during the next four to six weeks would support a diagnosis and lay the groundwork for an ongoing treatment plan.

It's important for you to keep track of your child's symptoms during a treatment trial and to follow instructions carefully. If you have followed the instructions and there is no improvement within the trial period, your doctor will likely consider another diagnosis.