CPT® Code 87340

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; hepatitis B surface antigen (HBsAg)

The CPT® Code 87340 refers to a laboratory test designed to detect the presence of Hepatitis B surface antigen (HBsAg) in serum or plasma. This test employs various immunoassay techniques, including enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). The detection of HBsAg is crucial as it indicates an active Hepatitis B virus (HBV) infection, which can lead to serious liver complications such as cirrhosis and hepatocellular carcinoma. The test can be performed qualitatively, providing a simple positive or negative result, or semiquantitatively, offering a measure of the antigen concentration. In the context of Hepatitis B, the presence of HBsAg signifies that the virus is present in the bloodstream, while the HBeAg test, which is related but distinct, is utilized to monitor the activity of the infection and the effectiveness of treatment. The HBsAg neutralization test serves as a confirmatory test for positive HBsAg results. Hepatitis B can be transmitted through blood and body fluids, and symptoms may include fever, fatigue, abdominal pain, and nausea, although some individuals may remain asymptomatic. The laboratory procedure involves obtaining a serum or plasma sample, which is then processed using the aforementioned immunoassay techniques to detect the antigen's presence through specific reactions that produce measurable signals, such as color changes or fluorescence.