Analysis of an iodide radioimmunoassay for 11-deoxicortisol measurement

• Published in: Arquivos brasileiros de endocrinologia e metabologia 2014-04, Vol.58 (3), p.232-236
• Main Authors: Madeira, João Luiz de Oliveira, Bussmann, Luciane Zgoda, Lima-Valassi, Helena Panteliou, Mendonça, Berenice Bilharinho de
• Format: Article
• Language: Portuguese
• Subjects: 17-alpha-Hydroxyprogesterone - analysis; Adrenal Hyperplasia, Congenital - diagnosis; Bias; Biomarkers - blood; Chromatography, High Pressure Liquid; Cortodoxone - blood; Humans; Iodine Radioisotopes; Radioimmunoassay - methods; Reagent Kits, Diagnostic - standards; Reference Standards; Reproducibility of Results; Sensitivity and Specificity; Tandem Mass Spectrometry
• ISSN: 1677-9487
• DOI: 10.1590/0004-2730000002616

Our aim was to correlate 11-deoxycortisol levels obtained by two currently available techniques for 11-deoxycortisol measurement: radioimmunoassay, and high performance liquid chromatography followed by tandem mass spectrometry (MS/MS). The latter is the gold standard method for steroid hormone measurement. We selected 88 samples and the results of these two methods were compared by Deming regression. The analytical sensitivity of the RIA was 0.30 ng/mL, with inadequate linearity and inadequate precision profile (34% of the samples had a CV ≥ 20%). From the selected samples, 54 had measurable levels of 11-deoxycortisol in both methods and were used in the comparison. The comparison of RIA with LC-MS/MS showed an overestimation of the results by RIA. The correlation coefficient was 0.610; linear regression slope was 3.751; and the intercept was 0.145, indicating a poor correlation between the two methods. We concluded that 11-deoxycortisol measured by radioimmunoassay, despite a good analytical sensitivity, showed very low specificity, precluding its use as a reliable method for 11-deoxycortisol measurement.