Fast Five Quiz: How Much Do You Know About Severe Allergic Asthma?

Zab Mosenifar, MD


October 18, 2019

Pulmonary function testing in adults and children (who are old enough to comply with testing) is considered the gold standard in asthma assessment. The result is expressed as a ratio of forced expiratory volume in 1 second (FEV1) over forced vital capacity (FVC). Obstruction is defined as FEV1/FVC < 70%; severe asthma is categorized as FEV1/FVC < 40%.

In vitro blood tests, such as the radioallergosorbent test (RAST), may be used only when comorbid dermatologic disease is suspected. Sputum and serum eosinophilia tests are not used to determine asthma severity, but some researchers have found them useful to guide treatment. An allergen-inhalation challenge is recommended only to determine the effect of continuous exposure to an allergen source, such as a family pet.

Learn more about pulmonary function testing here.


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