Nonchromatographic radioimmunoassay of plasma 11-deoxycortisol, for use in the metyrapone test, with polyethylene glycol as the precipant.
We have developed a simple, reliable radioimmunoassay for plasma 11-deoxycortisol. The method does not require chromatography but instead makes use of a simple extraction procedure which, in combination with the antibody characteristics, is highly specific for the metyrapone test. Polyethylene glycol was used to separate free and antibody-bound steroid. The smallest amount measurable is 15 pg (2.0 mug/liter of plasma). The method is shown to be precise and accurate. Intraassay precision of the method for two plasma pools was 26.7 plus or minus 2.5 mug/liter (CV equals 9.4%) and 61.2 plus or minus 3.7 mug/liter (CV equals 6.0%). The respective inter-assay precision was 27.0 plus or minus 1.7 mug/liter (CV equals 6.3%) and 59.9 plus or minus 2.3 mug/liter (CV equals 3.8%). The validity of the assay was further verified by evaluating the plasma 11-deoxycortisol response to metyrapone administration. The relative simplicity of the method and the commercial availability of all reagents, including antisera, makes this radioimmunoassay procedure practical for use in clinical laboratories.
D015065:17-Hydroxycorticosteroids / Q000097:blood*; D000937:Antigen-Antibody Reactions; D001667:Binding, Competitive; D003350:Cortodoxone / Q000097:blood*; D003429:Cross Reactions; D005069:Evaluation Studies as Topic; D006801:Humans; D007202:Indicators and Reagents; D008797:Metyrapone / Q000494:pharmacology*; D010912:Pituitary-Adrenal Function Tests; D011092:Polyethylene Glycols; D011485:Protein Binding; D011863:Radioimmunoassay / Q000379:methods; D013256:Steroids / Q000097:blood; D013329:Structure-Activity Relationship; D014316:Tritium
D015065:17-Hydroxycorticosteroids; D007202:Indicators and Reagents; D013256:Steroids; D014316:Tritium; D011092:Polyethylene Glycols; D003350:Cortodoxone; D008797:Metyrapone