CPT® Code 87451

Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], fluorescence immunoassay [FIA], immunochemiluminometric assay [IMCA]) qualitative or semiquantitative; polyvalent for multiple organisms, each polyvalent antiserum

The CPT® Code 87451 refers to a laboratory test designed to detect infectious agent antigens in blood and other body fluids through various immunoassay techniques. This code encompasses qualitative or semiquantitative testing methods, which include enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). These techniques utilize labeled antibodies that specifically bind to the target antigens present in the patient sample. The EIA and ELISA methods are particularly notable for their ability to detect minute quantities of antigens due to the use of a secondary enzyme-labeled antibody, which facilitates a chromogenic reaction resulting in a visible color change or fluorescence. This allows for the measurement of the infectious agent's presence in a qualitative or semiquantitative manner. The FIA method employs a fluorescent compound to indicate the binding of the detection antibody to the analyte, while the IMCA method utilizes a light emission device to quantify the antigen-antibody complex through chemiluminescence. It is important to note that code 87451 is specifically used for reporting polyvalent testing, which involves multiple organisms, with each polyvalent antiserum being utilized to identify serological subtypes of specific organisms that may have various strains present. For organisms that do not have a specific code for reporting, code 87449 should be used instead.