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Background: An erroneously high tacrolimus level was reported to a clinician. A root cause analysis investigation failed to determine the cause of the error. It was suspected that the incorrect preanalytical extraction reagent and procedure was used during testing; however, how this would affect the assayed drug concentration was unclear. Here we investigated the effect of the substitution of sirolimus, tacrolimus, and cyclosporine extraction reagents on assayed drug concentration., Methods: Tacrolimus, sirolimus, and cyclosporine concentration were measured on the Abbott Architect i2000 analyzer. Each assay requires a preanalytical extraction step, with a distinct reagent. We investigated the effect of the substitution of the extraction reagents and procedure between the 3 assays on the measured drug concentration. Two experiments were performed, one on samples of known drug concentration and one on samples with no drug present., Results: Substituting cyclosporine and sirolimus extraction procedures increased assayed tacrolimus concentrations from 5.6 to 8.47 (+51.25%) and 8.13 (+45.18%) ng/mL, respectively. Extraction procedure substitutions decreased assayed sirolimus from 13.63 to 4.60 (-66.25%) and 8.07 (-40.79%) ng/mL for cyclosporine and tacrolimus. Cyclosporine concentration increased from 274.60 to 391.30 (+42.50%) ng/mL using sirolimus extraction reagents and to 757.30 (+175.78%) ng/mL using tacrolimus extraction reagents. Cross-reactivity was observed between the tacrolimus assay and sirolimus and cyclosporine extraction reagents., Conclusions: Significant changes, both positive and negative, are observed in assayed drug concentration when incorrect extraction procedures are used in the Abbott i2000 tacrolimus, sirolimus, and cyclosporine assays. Preanalytic extraction procedures should be investigated when performing root cause analysis for erroneous therapeutic drug values., (© Association for Diagnostics & Laboratory Medicine 2024. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Cyclosporine (CsA) monitoring is essential for transplant success. We report a performance study of the recently released, fully automated Siemens ADVIA Centaur CsA assay., Methods: Whole blood samples from 248 transplant patients were prepared using a new 1-step extraction method. Performance evaluations vs. HPLC-tandem MS (LC-MS/MS), Abbott TDx and AxSYM assays were conducted according to CLSI EP5-A2 and EP9-A2 guidelines., Results: The correlation coefficient for LC-MS/MS and ADVIA Centaur was > or = 0.97 at each site, and for each transplant type. Regression analysis yielded y=0.94x+19 for all sites: 95% CI=0.91-0.96 (slope) and 10-28 (intercept). Absolute and relative bias was minimal for C0 and C2 sampling. Centaur vs. Abbott TDx and AxSYM assays: y = 0.72x+6, r = 0.98, 95% CI = 0.70-0.73 (slope), 3-9 (intercept); and y = 0.69x+18, r = 0.97, 95% CI = 0.67-0.71 (slope), 8-27(intercept). Within run CVs were 4.5%-7.1%, total CVs were 5.3%-7.7%., Conclusions: The ADVIA Centaur assay compared favorably with LC-MS/MS and Abbott assays, displaying good correlation for all transplant types and methods., (Copyright 2010 Elsevier B.V. All rights reserved.)

Abstract: Background: Cyclosporine (CsA) monitoring is essential for transplant success. We report a performance study of the recently released, fully automated Siemens ADVIA Centaur® CsA assay. Methods: Whole blood samples from 248 transplant patients were prepared using a new 1-step extraction method. Performance evaluations vs. HPLC–tandem MS (LC-MS/MS), Abbott TDx and AxSYM assays were conducted according to CLSI EP5-A2 and EP9-A2 guidelines. Results: The correlation coefficient for LC-MS/MS and ADVIA Centaur was≥0.97 at each site, and for each transplant type. Regression analysis yielded y =0.94x +19 for all sites: 95% CI=0.91–0.96 (slope) and 10–28 (intercept). Absolute and relative bias was minimal for C0 and C2 sampling. Centaur vs. Abbott TDx and AxSYM assays: y = 0.72x +6, r = 0.98, 95% CI = 0.70–0.73 (slope), 3–9 (intercept); and y = 0.69x +18, r = 0.97, 95% CI = 0.67–0.71 (slope), 8–27(intercept). Within run CVs were 4.5%–7.1%, total CVs were 5.3%–7.7%. Conclusions: The ADVIA Centaur assay compared favorably with LC-MS/MS and Abbott assays, displaying good correlation for all transplant types and methods. [Copyright &y& Elsevier]