Definition: method to measure the amount of a substance using an antibody against the substance for specificity and a radioactive label for detection and measurement.
Radioimmunoassay Definition - A highly sensitive and specific assay method that uses the competition between radiolabeled and unlabeled substances in an antigen-antibody reaction to determine the concentration of the unlabeled substance; it can be used to determine antibody concentrations or to determine the concentration of any substance against which specific antibody can be produced. Abbreviated RIA (source: NDI Foundation).
Radioimmunoassay (RIA) from Wikipedia - a scientific method used to test antigens (for example, hormone levels in the blood) without the need to use a bioassay. It involves mixing known quantities of radioactive antigen (frequently labeled with gamma-radioactive isotopes of iodine attached to tyrosine) with antibody to that antigen, then adding unlabeled or "cold" antigen and measuring the amount of labeled antigen displaced.
Steroid Radioimmunoassay - The following protocol is used in the laboratory of Professor John Wingfield at the University of Washington, Seattle. It is meant to be used under supervision in this lab. Normally it may take several weeks or even months to become proficient with the assay techniques. The Wingfield Lab is not responsible for consequences occurring when persons attempt to use this protocol on their own.
Radioimmunoassay Technique - The technique was introduced in 1960 by Berson and Yalow as an assay for the concentration of insulin in plasma. It represented the first time that hormone levels in the blood could be detected by an in vitro assay.