Radioimmunoassay

Abstract

Radioimmunoassay (RIA) is a method of measuring very minute amounts of substances employing the competitive binding of the substance to be measured and its radioisotope-labelled compound to the antibody. The method was first established by S. A. Berson and R. S. Yalow for insulin, and is now applied to a wide variety of hormones, body components and drugs. This brief review describes generalized assay procedures and the important reagents such as radioisotope-labelled compounds and radioiodination, assay standards, and preparation of antisera and their essential nature. Assay results given by RIA are not always agree with those obtained by biological assay if the antigenic determinant and biological active site are different. Such a characteristic feature of RIA led to the discoveries of the precursors of polypeptide hormones in their biosynthetic pathways, and gave further development of the endocrinological research field.