(EIA) Enzyme immunoassays have been developed as an alternative to radioimmunoassays. These methods use an enzyme to label either the antibody or antigen. The sensitivity of an enzyme immunoassay is similar to that for a radioimmunoassay, without the danger of radiation. One of the most widely used EIA for detection of infectious diseases is the ELISA (Enzyme Linked lmmuno Sorbent Assay) method.

See also Fluorescent Immunoassay.

(ELISA) An enzyme linked immuno sorbent assay, also called ELISA, or enzyme immunoassay (EIA) is a diagnostic tool to measure the concentration of a particular molecule.

See also Radioimmunoassay.

(FIA) A fluorescent immunoassay (also called fluoroimmunoassay) is an analytic assay method based on a fluorescent-labeled antigen or antibody. Fluorescent measurements are usually more sensitive than spectrophotometric measurements. Therefore, FIA methods have greater analytical sensitivity than enzyme immunoassay techniques.