title: Effects of some hematological parameters on whole blood tacrolimus concentration measured by two immunoassay-based analytical methods.
abstract: OBJECTIVE
  Tacrolimus (FK506) is a potent immunosuppressive drug used for prevention of rejection following transplantation. Several methods including immunoassays have been used for monitoring tacrolimus levels. The purpose of the present study was to compare the effects of various hematological parameters on whole blood tacrolimus concentrations which were measured with two different analytical methods, namely the microparticle enzyme immunoassay (MEIA II) and enzyme multiplied immunoassay technique (EMIT).
  
  
  METHODS
  The effects of hematological variables, namely hematocrit (Htc), hemoglobin (Hb), red blood cell (RBC), mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), red cell distribution width (RDW) and platelet (PLT) counts on tacrolimus concentrations (n = 2430 measurements) measured with EMIT (n = 1171) and MEIA II (n = 1259) methods in whole blood samples from kidney or liver or combined kidney-pancreas transplant patients (n = 162) during a 2-year post-transplantation period were compared.
  
  
  RESULTS
  The whole blood tacrolimus concentrations measured with MEIA II method were affected much more significantly by hematological parameters than those measured with EMIT method. In MEIA II method, RDW (r = 0.479, P < 0.01) showed a stronger correlation with tacrolimus concentration than Htc (r = -0.239, P < 0.01) in all patients. A negative significant correlation (r = -0.468, P < 0.01) was also observed between the Htc and tacrolimus concentration in patients with Htc values < or =25% in MEIA II method.
  
  
  CONCLUSIONS
  The results of the present study suggest that EMIT method might be preferred to MEIA II in determination of whole blood tacrolimus concentrations in anemic transplant patients. For better therapeutic drug monitoring, physicians should be aware of these assay differences. Evaluation of hematologic factors that affect the whole blood concentrations of tacrolimus may be helpful in deciding the dosage of this drug.
authors.affiliation: Akdeniz University, Faculty of Medicine, Central Laboratory, Clinical Biochemistry Unit, 07070 Antalya, Turkey. halideakbas@akdeniz.edu.tr
authors.forename: S Halide
authors.initials: SH
authors.lastname: Akbas
authors.forename: Sebahat
authors.initials: S
authors.lastname: Ozdem
authors.forename: Serkan
authors.initials: S
authors.lastname: Caglar
authors.forename: Murat
authors.initials: M
authors.lastname: Tuncer
authors.forename: Alihan
authors.initials: A
authors.lastname: Gurkan
authors.forename: Levent
authors.initials: L
authors.lastname: Yucetin
authors.forename: Yesim
authors.initials: Y
authors.lastname: Senol
authors.forename: Alper
authors.initials: A
authors.lastname: Demirbas
authors.forename: Meral
authors.initials: M
authors.lastname: Gultekin
authors.forename: F Fevzi
authors.initials: FF
authors.lastname: Ersoy
authors.forename: Mustafa
authors.initials: M
authors.lastname: Akaydin
mesh_terms: D000328:Adult; D000368:Aged; D016903:Drug Monitoring / Q000379:methods; D017248:Enzyme Multiplied Immunoassay Technique; D005260:Female; D005500:Follow-Up Studies; D006403:Hematologic Tests; D006801:Humans; D007124:Immunoenzyme Techniques; D007166:Immunosuppressive Agents / Q000097:blood*; D016030:Kidney Transplantation; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D016035:Pancreas Transplantation; D012189:Retrospective Studies; D016559:Tacrolimus / Q000097:blood*; D013997:Time Factors; D014421:Turkey
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus