NIH, National Cancer Institute, Division of Cancer Treatment and Diagnosis (DCTD) NIH - National Institutes of Health National Cancer Institute DCTD - Division of Cancer Treatment and Diagnosis
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Effect of citrate concentration in specimen collection tubes on the International Normalized Ratio.

Author(s): Danielson CF, Davis K, Jones G, Benson J, Arney K, Martin J

Publication: Arch Pathol Lab Med, 1997, Vol. 121, Page 956-9

PubMed ID: 9302927 PubMed Review Paper? No

Purpose of Paper

The purpose of this paper was to determine the effects of citrate concentration and type of coagulometer used on prothrombin time (PT) and International Normalized Ratio (INR) in plasma from patients on warfarin anticoagulant therapy.

Conclusion of Paper

For both coagulometers, plasma in 3.2% citrate tubes had significantly lower mean INR than that in 3.8% citrate tubes. In several cases, while specimens from one tube fell within the therapeutic range, the duplicate specimen with the alternate citrate concentration had an INR indicating an increased risk for bleeding or thromboembolism. The authors recommend that for PT testing, 3.2% citrate tubes be used rather than 3.8% citrate tubes. No statistical comparison between the two coagulometers is presented, however, the MLA 1000 coagulometer measured higher mean INRs after transport for both 3.2% and 3.8% citrate specimens than the ACL 300 in untransported specimens.

Studies

  1. Study Purpose

    The purpose of this study was to determine the effects of citrate concentration (3.2% versus 3.8%) and type of coagulometer used on PT and INR in plasma from patients on warfarin anticoagulant therapy. All plasma was frozen immediately and stored at -70 degrees C or lower. A subset of specimens was shipped on dry ice to an alternate laboratory for analysis on a different coagulometer (MLA 1000). The two laboratories thawed specimens in 37 degrees C water baths 30 min prior to analysis.

    Summary of Findings:

    For both coagulometers, the mean INR calculated from PT measured in plasma from 3.2% citrate tubes was significantly lower than the mean INR calculated from PT measured in plasma from 3.8% citrate tubes (p<0.001). In several cases, while specimens from one tube fell within the therapeutic range, the duplicate specimen with the alternate citrate concentration had an INR indicating an increased risk for bleeding or thromboembolism. The authors recommend that for PT testing, 3.2% citrate tubes be used rather than 3.8% citrate tubes. No statistical comparison between the two coagulometers is presented, however, the MLA 1000 coagulometer measured higher mean INRs for both 3.2% and 3.8% citrate specimens than the ACL 300, but differences may also be attributable to storage or transport effects.

    Biospecimens
    Preservative Types
    • Frozen
    Diagnoses:
    • Not specified
    Platform:
    AnalyteTechnology Platform
    Morphology Hematology/ auto analyzer
    Pre-analytical Factors:
    ClassificationPre-analytical FactorValue(s)
    Biospecimen Acquisition Anticoagulant Citrate
    Multiple concentrations evaluated
    Hematology/ auto analyzer Specific Technology platform MLA 1000
    ACL 300 coagulometer
    Storage Between site transportation method Not transported
    Unspecified transport method
    View more

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