Evaluation of cortisol assay by chemiluminescent enzyme immunoassay

Abstract

We conducted a basic examination of a cortisol-measuring reagent by chemiluminescent immunoassay as a principle, which was newly developed as a reagent for the AIA-CL system (Tosoh Co., Ltd.). The coefficients of variances (CVs) for intra- and inter-assays using control samples were between 2.3 and 5.8%. They showed good linearity from 0 to 60.0 μg/dL, and the limit of quantitation was 0.65 μg/dL. This new method is characterized by a reduction in the measurement time and an increase in the specificity related to monoclonal antibody switching from a polyclonal antibody. This improves the cross-reactivity with synthetic steroids, which has been a limitation, suggesting that intrinsic cortisol can be measured more accurately by this new method than by the conventional method. This method may be useful for routine examinations.