title: The Emit® 2000 Cyclosporine Specific Assay, Extended Range: development of an application protocol for the V-Twin® analyzer.
abstract: We evaluated a new protocol for measurement of cyclosporine A (CsA) 2 H after dose (C2) on the V-Twin® analyzer. Imprecision, recovery, and linearity were determined using CsA-spiked blood pools. Accuracy was evaluated using specimens from renal, cardiac, and liver transplant patients, and results were compared with those from liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the Abbott TDx®/TDxFLx® assay. Cross-reactivity and interferences were assessed in the presence of 800 ng/mL CsA. Imprecision coefficients of variation were 3.3%-4.8% (within run) and 5.9%-8.7% (total). Recovery was within 10% of the expected values. Linearity was 350-2,000 ng/mL. Calibration was stable for ≥ 2 weeks. Method comparison showed regression statistics: V-Twin® = 1.01 × LC tandem MS + 36.1, r = 0.971; V-Twin® = 1.13 × Abbott - 92.4, r = 0.969. Metabolite cross-reactivity and interference (endogenous substances and drugs) were within ±10%. The C2 protocol on the V-Twin® analyzer provides acceptable assay performance and accurate determination of whole blood CsA drawn at 2 H after dose.
authors.affiliation: Siemens Healthcare Diagnostics Inc., Newark, DE 19702, USA. nihmat.morjana@siemens.com
authors.forename: Nihmat
authors.initials: N
authors.lastname: Morjana
authors.forename: Harriet
authors.initials: H
authors.lastname: Yau
authors.forename: Diane
authors.initials: D
authors.lastname: Rea
authors.forename: Doris
authors.initials: D
authors.lastname: Ruttle
authors.forename: Heather
authors.initials: H
authors.lastname: Jones
authors.forename: Gerald
authors.initials: G
authors.lastname: Siefring
authors.forename: Robert
authors.initials: R
authors.lastname: Christenson
mesh_terms: D002138:Calibration; D003429:Cross Reactions; D016572:Cyclosporine / Q000097:blood* / Q000276:immunology; D016027:Heart Transplantation; D006801:Humans; D007124:Immunoenzyme Techniques / Q000295:instrumentation* / Q000379:methods; D007166:Immunosuppressive Agents / Q000097:blood*; D016030:Kidney Transplantation; D016031:Liver Transplantation; D012680:Sensitivity and Specificity
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine