CPT® Code 87328

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; cryptosporidium

The CPT® Code 87328 refers to a laboratory test designed to detect the presence of cryptosporidium antigen in a fecal sample using various immunoassay techniques. Cryptosporidium is a microscopic, one-celled parasite responsible for the diarrheal illness known as cryptosporidiosis. This parasite invades the intestinal walls, leading to symptoms such as watery diarrhea, dehydration, loss of appetite, weight loss, and abdominal cramps, which can persist for several weeks and may recur sporadically. The test can be performed using several immunoassay methods, including enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). Each of these techniques operates on the principle of detecting specific antigens by utilizing antibodies that bind to the target antigen. The EIA and ELISA methods are particularly sensitive, capable of identifying minute quantities of the antigen through a colorimetric reaction that occurs when a secondary enzyme-labeled antibody is introduced. This reaction results in a visible color change, which can be quantitatively assessed. The FIA method employs a fluorescent compound to detect the binding of the antibody to the antigen, while the IMCA method utilizes chemiluminescent substances to measure the light emitted from the antigen-antibody complex. Overall, this test is crucial for diagnosing cryptosporidiosis and guiding appropriate treatment options.