title: Evaluation of the New Siemens Tacrolimus Assay on the Dimension EXL Integrated Chemistry System Analyzer: Comparison With an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method.
abstract: Many patients are maintained at the lower end of the tacrolimus (TAC) reference range (3-7 ng/mL), requiring the use of analytical methods displaying a very low limit of quantification for their follow-up. Therefore, the new Dimension TAC, based on affinity chrome-mediated immunoassay technology, was evaluated on the Dimension EXL Integrated Chemistry System (Siemens Healthcare Diagnostics Inc). The aims of this study were (1) to evaluate the analytical performances with special emphasis on sensibility at low levels of TAC, (2) to compare the results with an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS) method.
  
  
  
  Analytical performance (imprecision, linearity, limit of detection, and limit of quantification) was evaluated. Comparison to UPLC/MS/MS was performed on 106 whole blood samples from 88 transplant recipients using regression analysis and Bland-Altman plot analysis.
  
  
  
  Repeatability and within-laboratory coefficients of variation were <6% at mean TAC control levels of 3.7, 11.7, and 19.2 ng/mL. Linearity was confirmed between 1.0 and 22 ng/mL. Passing-Bablok regression analysis of Siemens TAC assay in comparison with UPLC/MS/MS values displayed a slope of 1.09 and an intercept of -0.42. Using Bland-Altman analysis, the mean bias was 0.27 ng/mL with 1.96 SD limits of -2.14 and 2.67 ng/mL.
  
  
  
  The new Dimension TAC immunoassay on the EXL analyzer demonstrated reliable and reproducible performances allowing routine monitoring in transplant patients, even at TAC concentrations at the lower end of the therapeutic range.
authors: *Laboratoire de Biochimie, CHRU de Montpellier, PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR 9214; †Laboratoire de Biochimie, CHRU de Montpellier, University of Montpellier, INSERM U1061; ‡Service de Néphrologie, Dialyse et Transplantation, CHRU Montpellier, Univ Montpellier 1; and §Service d'Hépato-Gastroentérologie et transplantation, CHRU Montpellier, Univ Montpellier 1, Montpellier, France.
authors: Anne-Sophie
authors: AS
authors: Bargnoux
authors: Thibault
authors: T
authors: Sutra
authors: Stéphanie
authors: S
authors: Badiou
authors: Nils
authors: N
authors: Kuster
authors: Anne-Marie
authors: AM
authors: Dupuy
authors: Georges
authors: G
authors: Mourad
authors: Georges-Philippe
authors: GP
authors: Pageaux
authors: Moglie
authors: M
authors: Le Quintrec
authors: Jean-Paul
authors: JP
authors: Cristol
mesh_terms: D001681:Biological Assay / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007166:Immunosuppressive Agents / Q000097:blood*; D057230:Limit of Detection; D008297:Male; D008875:Middle Aged; D016559:Tacrolimus / Q000097:blood*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus