Preliminary analytical evaluation of the fully automated Cobas i601 LC-MS/MS system for steroid hormones and vitamin D in a clinical laboratory.
Abstract
Background
Fully automated liquid chromatography-tandem mass spectrometry (LC-MS/MS) platforms aim to combine the analytical specificity and sensitivity of mass spectrometry with the workflow efficiency of automated routine analyzers. This study performed a preliminary analytical evaluation of the Cobas i601 LC-MS/MS system for estradiol, testosterone, aldosterone, androstenedione, 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2D), including method comparison with routine immunoassays in a real-world clinical laboratory setting.
Methods
Imprecision, bias, and linearity were assessed according to Clinical and Laboratory Standards Institute (CLSI) EP10-A3 using three levels of commercial quality control material. Results were compared to analytical performance specifications (APS) based on biological variation. Method comparison and bias estimation with routine immunoassays were performed following CLSI EP09-A3 using serum samples. Predicted biases at clinical decision levels (CDL) were evaluated against allowable limits.
Results
All assays demonstrated acceptable analytical performance (maximum coefficient of variation 3.4%; maximum bias 7.8%) and fulfilled predefined APS. Linearity was confirmed across the tested ranges (p > 0.05). Testosterone showed acceptable biases at CDL (1.7% to 9.3%) according to the predefined APS, although greater variability was observed at lower concentrations. In contrast, androstenedione, estradiol, aldosterone and 25(OH)D exhibited substantial systematic bias compared with immunoassays (20%, -36.5%, -28.5% and - 16% respectively at intermediate CDL).
Conclusions
The Cobas i601 demonstrated acceptable analytical performance in this first preliminary evaluation. However, systematic differences relative to immunoassays for several analytes highlight the need for close clinician-laboratory communication when implementing this new automated LC-MS/MS platform, and underscore the need for further analytical and clinical validation.