Analytical and clinical evaluation of an automated cortisol assay on the ACS: 180®

Objective: To evaluate the analytical and clinical performance of an automated assay for serum cortisol on the ACS: 180®. Methodology: Analytical performance (sensitivity, precision, linearity, carryover, interference) was assessed using standard laboratory protocols. The values obtained on the ACS for protocol specimens were compared to those obtained with a number of other automated assays on the ES300, TDx FLx, and Stratus. Results: The assay exhibited within-run and total coefficients of variation of <4% and 8.1%, respectively. Good correlation was observed among all the assays for patient specimens for a.m. and p.m. cortisol values; however, the mean values for the ACS were approximately 10–15% higher than those with the ES300 and Stratus and 5% lower than those with the TDx FLx. The reference range for all 4 assays as determined in a local population were higher than those claimed by the manufacturers. Good agreement among the assays were obtained for patients undergoing dexamethasone suppression and ACTH stimulation tests. Conclusion: The cortisol assay on the ACS:180 is accurate and precise and provides results that are clinically comparable to other automated assays. The random access capabilities of the instrument can facilitate workstation consolidation for improved laboratory efficacy.