CPT® Code 87400

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; Influenza, A or B, each

The CPT® Code 87400 refers to a laboratory test designed to detect the presence of Influenza A or B antigens in a sample using various immunoassay techniques. These techniques include enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). Influenza A and B are viral pathogens responsible for causing influenza, commonly known as the flu, which can lead to a range of symptoms from mild respiratory issues to severe complications such as pneumonia. Influenza A is notable for its ability to infect both humans and animals, including birds and swine, while Influenza B primarily affects humans. The testing process involves obtaining a sample, which may be blood or respiratory secretions, and preparing it for laboratory analysis. The sample is either placed in a fixative or sent fresh to the laboratory. The immunoassay techniques employed in this test are highly sensitive and capable of detecting even minute quantities of the influenza antigen. For instance, EIA and ELISA work by binding the antigen to a specific antibody, followed by the addition of a secondary enzyme-labeled antibody that facilitates detection through a colorimetric reaction. This reaction results in a visible color change, which can be quantitatively assessed. Similarly, FIA utilizes a fluorescent compound to detect the binding of the antibody to the antigen, while IMCA employs chemiluminescent substances to identify and quantify the antigen-antibody complex through light emission. The results of this test can be reported qualitatively or semi-quantitatively, providing valuable information for diagnosing influenza infections.