title: Performance of a no-pretreatment tacrolimus assay on the Dade Behring Dimension RxL clinical chemistry analyzer.
abstract: BACKGROUND
  Therapeutic drug monitoring for tacrolimus is important for organ transplant patients receiving this immunosuppressant. Current available assays for tacrolimus require sample pre-treatment and operate in a batch mode. Here a no-pretreatment tacrolimus assay, performed on the Dade Behring Dimension analyzer is compared to the Abbott IMx tacrolimus assay and to an LC/MS/MS method.
  
  
  METHODS
  Whole blood samples from 2 medical centers and different transplant types (kidney n=103, liver n=81, heart n=27, pancreas n=16, bone marrow n=9, [corrected] lung n=7), were obtained and tacrolimus quantified by each of the 3 assays.
  
  
  RESULTS
  The lower limit of the linear range was 1.2 ng/ml on the Dimension assay. Total imprecision was 9.8% and within-run imprecision was 9.6% at a tacrolimus concentration of 3.4 ng/dL. Passing-Bablock regression analysis determined the following relationships: DIMN=(1.16) LC/MS - 0.43, r=0.90 and DIMN=(0.99)IMx - 0.35, r=0.87.
  
  
  CONCLUSIONS
  The Dade Behring Dimension [corrected] Tacrolimus assay has adequate imprecision and correlates well with the reference method of LC/MS/MS. The assay appears suitable for clinical use, and has the advantages of not requiring a pretreatment step and the ability to be performed in a random-access mode.
authors.affiliation: Department of Pathology and Immunology, Division of Laboratory and Genomic Medicine, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
authors.forename: Megan A
authors.initials: MA
authors.lastname: Griffey
authors.forename: Karl G
authors.initials: KG
authors.lastname: Hock
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Kilgore
authors.forename: Tie Q
authors.initials: TQ
authors.lastname: Wei
authors.forename: Show-Hong
authors.initials: SH
authors.lastname: Duh
authors.forename: Robert
authors.initials: R
authors.lastname: Christenson
authors.forename: Mitchell G
authors.initials: MG
authors.lastname: Scott
mesh_terms: D002853:Chromatography, Liquid; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods*; D007166:Immunosuppressive Agents / Q000097:blood*; D013058:Mass Spectrometry; D016377:Organ Transplantation; D016559:Tacrolimus / Q000097:blood*
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus