Diagnosis

Asthma can be hard to diagnose. Your child's doctor will consider the symptoms and their frequency and your child's medical history. Your child might need tests to rule out other conditions and to identify the most likely cause of the symptoms.

A number of childhood conditions can have symptoms similar to those caused by asthma. To complicate the issue further, these conditions also commonly occur with asthma. So your child's doctor will have to determine whether your child's symptoms are caused by asthma, a condition other than asthma, or both asthma and another condition.

Conditions that can cause asthma-like symptoms include:

• Rhinitis
• Sinusitis
• Acid reflux or gastroesophageal reflux disease (GERD)
• Airway abnormalities
• Dysfunctional breathing
• Respiratory tract infections such as bronchiolitis and respiratory syncytial virus (RSV)

The following are tests your child might need.

• Lung function tests (spirometry). Doctors diagnose asthma with the same tests used to identify the disease in adults. Spirometry measures how much air your child can exhale and how quickly. Your child might have lung function tests at rest, after exercising and after taking asthma medication.

  Another lung function test is brochoprovocation. Using spirometry, this test measures how your lungs react to certain provocations, such as exercise or exposure to cold air.

• Exhaled nitric oxide test. If the diagnosis of asthma is uncertain after lung function tests, your doctor might recommend measuring the level of nitric oxide in an exhaled sample of your child's breath. Nitric oxide testing can also help determine whether steroid medications might be helpful for your child's asthma.

The asthma tests used, however, aren't accurate before 5 years of age. For younger children, your doctor will rely on information you and your child provide about symptoms. Sometimes a diagnosis can't be made until later, after months or even years of observing symptoms.

Allergy tests for allergic asthma

If your child seems to have asthma that's triggered by allergies, the doctor might recommend allergy skin testing. During a skin test, the skin is pricked with extracts of common allergy-causing substances, such as animal dander, mold or dust mites, and observed for signs of an allergic reaction.