Improvement in the Precision and Accuracy Of a Commercially Available Insulin Radioimmunoassay Kit

Abstract

Experience of more than one year with a commercially available insulin kit is reviewed. While the method is adequate as delivered, it suffers from higher than desired nonspecific binding (NSB) values and greater than desired intra-assay and interassay variations. Modifications can be made, however, which will reduce the NSB % and enhance the precision—40% reduction in standard deviation (s.d.) at 70 μ U— and accuracy of the assay. Modifications involve incubation times, pre-cooling tubes before addition of reagents, and changes in technique, making them particularly well suited to small departments without facilities and personnel to do more extensive assay optimization.