title: Discrepant cortisol values: comparison of radioimmunoassay and competitive protein binding technics.
abstract: Radioimmunoassays are expected to yield values representing the antigen, i.e., insulin, growth, cortisol, etc. employed in producing the antibody. However, in a recent study of a synthetic ACTH which involved the measurement of cortisol levels (1), we found that above 20gamma%, the radioimmunoassay (RIA) yields cortisol values distinctly above those obtained with the competitive protein binding (CPB) technic. We now suggest a possible explanation for this discrepancy and have calculated a correction factor.
mesh_terms: D001667:Binding, Competitive; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D011485:Protein Binding; D011863:Radioimmunoassay / Q000379:methods*
chemical_list: D006854:Hydrocortisone