Is the automated Elecsys tacrolimus assay on the Roche cobas e 602 analyzer an acceptable replacement for a liquid chromatography-tandem mass spectrometry-based assay?

The 2 major challenges for implementation of the tacrolimus ECLIA assay are the postextraction sample stability and the significant proportional bias observed compared with the LC-MS/MS reference method. The 30-minute window for analysis of extracted samples is a practical challenge to the routine workflow of the core laboratory. In addition, disagreement between the immunoassay and LC-MS/MS methods can lead to discordant clinical interpretations and ultimately affect patient care.