CPT® Code 87449

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; not otherwise specified, each organism

The CPT® Code 87449 refers to a laboratory test designed to detect infectious agent antigens in blood and other body fluids through various immunoassay techniques. This code encompasses a range of methodologies, including enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). Each of these techniques employs specific biochemical processes to identify and quantify antigens, which are substances that provoke an immune response. The EIA and ELISA methods utilize labeled antibodies that bind to the target antigens, producing a chromogenic reaction that results in a visible color change, thereby allowing for qualitative or semiquantitative measurement of the antigen's presence. The FIA method employs fluorescent compounds to detect the binding of antibodies to the antigens, while the IMCA method uses chemiluminescent substances to measure the light emitted from the antigen-antibody complex. This code is specifically used for reporting tests that do not have a dedicated code for the detection of infectious agent antigens using these immunoassay techniques, ensuring accurate billing and documentation for each organism tested. For tests involving multiple organisms, the CPT® Code 87451 should be used, which pertains to polyvalent testing that identifies serological subtypes of organisms.