[Development of hormone assay methods].

Abstract

Before the introduction of radioimmunoassay most hormones were measured by bioassay and/or chemical methods. The sensitivity of these methods was low, so large amounts of samples were needed to perform hormone determinations. In 1959, Berson and Yalow, first applied radioimmunoassay to the measurement of insulin, after which many protein hormones were determined by this method. Subsequently, radioimmunoassays were developed for small peptide molecules as well as for non-peptide hormones such as thyroid hormones and steroid hormones. Two site immunoradiometric assay in which one antibody was immobilized and another labeled with 125I becomes popular, due to its high sensitivity and the development of monoclonal antibody production by the hybridoma technique. Although radioimmunoassays immunoradiometric assays are sensitive and robust techniques, there has been a growing interest for non-istotopic alternatives since early 1980s. Recently, non-istopic immunoassay methods utilizing chemiluminescence, fluorescence and enzymes as labels are widely used. Chemiluminescence immunoassays, fluorescence immunoassays and enzymic immunoassays with fluorometric detection have resulted in sensitivities adequate to replace radioimmunoassays. Since hormone immunoassays are all dependent upon immunologic properties of hormones, the simultaneous measurement of hormones by a biologic method sometimes shows discrepancies in the hormone concentrations. Hormone assay methods employing biologically specific receptors was introduced, but used not so widely due to the unstability of hormone receptors. In vitro bioassay, is easy to perform and has high sensitivity and applicable for definite hormones. Isotopic and non-isotopic immunoassays are simple and quite useful, but other methods such as radioreceptor assay and bioassay-especially in vitro bioassay are also recommendable to run with radioimmunoassays.