immunoassay

A test that uses the binding of antibodies to antigens to identify and measure certain substances. Immunoassays may be used to diagnose disease. Also, test results can provide information about a disease that may help in planning treatment (for example, when estrogen receptors are measured in breast cancer).

An detection system for a particular molecule, which exploits the specific binding of an antibody raised against it. For measurement, the antibody can incorporate a radioactive or fluorescent label, or be linked to an enzyme which catalyses an easily monitored reaction such as a change in colour (see: ELISA ). Synonym: immunodiagnostics.