Inclusion of an extraction step in a kit for direct assay of androstenedione

Results obtained by the Diagnostic Systems Laboratories (DSL), I-125 direct androstenedione kit performed according to the package insert and after th e introduction of an extraction step were compared with a reference method that used a tritiated radioligand, Significantly higher results were obtain ed by the direct assay as compared to the tritiated method, whereas excelle nt correlation was obtained between the two after the introduction of an ex traction step in the direct procedure. The discordance between the results by the DSL direct and extraction methods may be due to matrix effects and n on-specific interferences, The performance characteristics of the kit were evaluated and were found to be satisfactory. Twenty apparently healthy indi viduals gave a range of 26-228 ng/dL for males and 36-162 ng/dL for females in the DSL extraction assay.