Effects of some hematological parameters on whole blood tacrolimus concentration measured by two immunoassay-based analytical methods.
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.
Akbas
S Halide
SH
Akdeniz University, Faculty of Medicine, Central Laboratory, Clinical Biochemistry Unit, 07070 Antalya, Turkey. halideakbas@akdeniz.edu.tr
Ozdem
Sebahat
S
Caglar
Serkan
S
Tuncer
Murat
M
Gurkan
Alihan
A
Yucetin
Levent
L
Senol
Yesim
Y
Demirbas
Alper
A
Gultekin
Meral
M
Ersoy
F Fevzi
FF
Akaydin
Mustafa
M
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
D007166:Immunosuppressive Agents; D016559:Tacrolimus