title: Effects of hematocrit value on microparticle enzyme immunoassay of tacrolimus concentration in therapeutic drug monitoring.
abstract: The effects of hematocrit (Ht) value on microparticle enzyme immunoassay (MEIA) of tacrolimus concentration were examined in 1063 whole-blood samples from 42 transplant recipients (13 liver, 20 kidney, and 9 bone marrow transplantations). MEIA guarantees the test's assay quality for blood tacrolimus in samples with Ht values of 25% to 45%. However, 129 samples (29.3%) obtained from liver transplant recipients and 107 samples (61.5%) from bone marrow transplant recipients had lower Ht (<25%). Further, 81 blood samples (18.1%) with Ht > 45% were observed in kidney transplant patients. Twenty-five whole-blood samples with low Ht were tested by 3 assay methods for tacrolimus: MEIA, modified, corrected MEIA (cMEIA), and enzyme-linked immunosorbent assay (ELISA). MEIA gave higher blood concentrations of tacrolimus than ELISA (16.1 versus 11.0 ng/mL, P < 0.001). This difference was generated by overestimation in MEIA and was not observed in samples with normal Ht. This overestimation was eliminated by using cMEIA on samples with low Ht values: there was no difference in blood tacrolimus concentration between cMEIA and ELISA (12.3 versus 11.0 ng/mL). ELISA or cMEIA should be used for tacrolimus assay in samples obtained from bone marrow transplant recipients with anemia and from liver and kidney transplant recipients with unstable Ht values.
authors.affiliation: Department of Pharmacy, Tsukuba University Hospital, Tsukuba, Ibaraki 305-8576, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tomita
authors.forename: Masato
authors.initials: M
authors.lastname: Homma
authors.forename: Kenji
authors.initials: K
authors.lastname: Yuzawa
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ohkohchi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hori
authors.forename: Michio
authors.initials: M
authors.lastname: Kaneko
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kojima
authors.forename: Toshiro
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Yukinao
authors.initials: Y
authors.lastname: Kohda
mesh_terms: D016026:Bone Marrow Transplantation / Q000473:pathology / Q000502:physiology; D002675:Child, Preschool; D016903:Drug Monitoring / Q000379:methods* / Q000592:standards; D005260:Female; D006400:Hematocrit / Q000379:methods / Q000592:standards*; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods* / Q000592:standards* / Q000639:trends; D007166:Immunosuppressive Agents / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use; D016030:Kidney Transplantation / Q000473:pathology / Q000502:physiology; D016031:Liver Transplantation / Q000473:pathology / Q000502:physiology; D008297:Male; D011237:Predictive Value of Tests; D016559:Tacrolimus / Q000737:chemistry* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus