(RIA) A radioimmunoassay is an in vitro assay test in which very small quantities of hormones, drugs and other substances in blood, urine, etc. can be measured by using specific antibodies or antigens which have been labeled with radioactive tracers. Since the patient does not receive the radioactive material, there is no patient radiation exposure.
Radioimmunoassays are usually replaced by fluoroimmunoassay and enzymimmunoassay to avoid the use of radioactive materials.

See also Bioassay, Fluorescent Immunoassay, Protein Binding Assay, Radioassay, and Berson Salomon.

Salomon Berson developed in 1959 (published in 1960) together with Rosalyn S. Yalow the radioimmunoassays.

See Radioimmunoassay.

(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.

A bioassay is a medical test to measure, and quantify radionuclides in the body by direct (in vivo) or indirect (in vitro) analysis of tissues or excretions from the body.

See also Radioimmunoassay.

(CPBA) The competitive protein binding analysis is a radioimmunoassay utilizing radioactive isotope labeled antigens, which compete with unlabeled antigens for chemical bond with specific antibodies. Binding proteins occur naturally and have affinity for other substances.