Cross-method comparison of serum androstenedione measurement with respect to the validation of a new fully automated chemiluminescence immunoassay.

OBJECTIVES: Androstenedione is an androgen produced as an intermediate product of the biosynthesis of testosterone and estradiol in testicles, ovaries and also in the adrenal cortex. Measurement is used for diagnosing and differentiating hirsutism and virilisation, enzyme deficiencies of the steroid hormone biosynthesis, and in suspicion of androgen-producing tumors.

METHODS: Specimens included de-identified residual serum specimens submitted for routine testing and banked adult and pediatric sera. Samples were measured with tandem mass spectrometry, two automated immunoassays, the newly developed DiaSorin LIAISON androstenedione assay, the Immulite assay, and a radioimmunoassay (Beckman Coulter) according to manufacturer's protocols. All methods were correlated, and the analytical sensitivity, linearity and imprecision of each assay determined. Diagnostic accuracy with respect to detection of PCOS in women was evaluated by verifying the respective reference ranges of the different assays and receiver operating characteristic (ROC) curve analysis.

RESULTS: Due to the methodology, LC-MS/MS demonstrated the highest analytical specificity, good performance and excellent diagnostic accuracy. The best agreement was found with the LIAISON chemiluminescent immunoassay method. Due to its lower analytical sensitivity, the measured values in children were often outside the measuring range. Although, the coefficient of correlation between LC-MS/MS and the Beckman Coulter radioimmunoassay was lower, the assay demonstrated the best analytical sensitivity and a similar diagnostic accuracy in adults. The Immulite androstenedione chemiluminescent immunoassay showed the poorest performance and was not interchangeable with the other assays.

CONCLUSIONS: These data suggest the LIAISON androstenedione assay may be a suitable alternative for the measurement of androstenedione in serum of adult patients with all advantages of a fully automated assay.