PC20

PC20 is a term used in multiple domains, but it is best known in respiratory medicine as a measure of airway hyperresponsiveness. In this medical context, PC20 denotes the provocative concentration of a bronchoconstrictor that induces a 20% drop in forced expiratory volume in one second (FEV1) during a methacholine or histamine challenge test. The test involves inhaling progressively higher concentrations of the agent and monitoring lung function; PC20 is estimated from the resulting dose–response curve by interpolation. A lower PC20 value indicates greater airway sensitivity.

Clinically, PC20 helps assess asthma and other airway diseases and is interpreted alongside symptoms, baseline lung function, and other measurements. It provides information about the degree of airway responsiveness, but there is no single universal cutoff that applies in all settings. Values can be influenced by factors such as age, baseline FEV1, smoking status, and the specific challenge protocol used. Therefore, interpretation relies on established reference values for the particular test method and clinical context.

Outside medicine, PC20 may appear as a model number, product code, or designation in other fields. In those contexts, the meaning is domain-specific and not standardized. When encountering the term PC20, it is important to consider the relevant domain and accompanying context to determine its precise meaning.