Challenge Tests for Asthma

Topic Overview

Exercise challenge and inhalation challenge tests are sometimes used to diagnose asthma and workplace asthma (occupational asthma).

Exercise challenge test

In an exercise challenge test, spirometry is done before and after you exercise on a treadmill or an exercise bicycle. Spirometry measures how much and how quickly you can breathe air in and out. An exercise challenge test can see what effect exercise has on airflow.

Most people with asthma have some decreased airflow during or after exercise. But most people who have asthma do not need an exercise challenge test.

Inhalation challenge test

An inhalation challenge test measures how much and how quickly you can breathe air in and out before and after taking medicine. Spirometry may be done before and after you are given an inhaled medicine, such as methacholine or histamine, or after breathing cold air. The test may be repeated for different doses of the medicine.

An inhalation challenge test is rarely needed to diagnose asthma. But it may be used to:

• See whether the tubes that carry air to the lungs (bronchial tubes) overreact to breathing cold air or to inhaling methacholine or histamine. This may support a diagnosis of asthma.
• Document that asthma is present when the diagnosis is unclear based on medical history, physical exam, and initial treatment.

You may also have a specific inhalation challenge. In this test, your doctor exposes you to a small amount of the material that may be causing your symptoms and then measures your lung function.