CLSI H54 A : 1ED 2005

Abstract
Committee Membership
Foreword
1 Scope
2 Standard Precautions
3 Definitions
Part I. Detailed Version
4 Laboratory Monitoring of AVK Therapy
   4.1 Recommended Method
   4.2 Limitations of the INR System
   4.3 Optimizing Current PT/INR Test Systems (Prior to
        Local Verification or Calibration)
5 Recommendations for Verification of the PT/INR Test
   System
   5.1 Verification of INR Results
6 Recommendations for Further Improvement of the PT/INR
   Test System (INR Calibration)
   6.1 PT/INR Calibration
   6.2 General Guidelines for the Use of Certified Plasmas
   6.3 Frequency of Calibration
   6.4 Tissue Factor Species Effects
7 PT/INR System Calibration to Determine Local ISI
   7.1 Procedure for Local ISI (ISI[LS] Determination)
   7.2 Number of Certified Plasmas Required for Local ISI
        Calibration
   7.3 Local System Verification Following ISI Calibration
   7.4 Criteria for Acceptance of Locally Calculated ISI
   7.5 Interpretation of Patient Test Results
8 PT/INR System Calibration to Determine Direct INR
   8.1 Recommended Number and Preparation of Certified
        Plasmas
   8.2 Procedure for Preparation of a Direct INR Calibration
        Line
   8.3 Interferences
   8.4 Guidelines for Determining Result Acceptance
   8.5 Interpretation of Patient Test Results
9 Choice of Verification/Calibration Material
   9.1 Method of Preparation of Certified Reference
        Materials
   9.2 Validation of Certified Plasmas
   9.3 Documentation Required by Manufacturers
Part II. Abbreviated Version for Laboratorians
10 Introduction
   10.1 Limitations of the INR System
   10.2 ISI Value Assigned by the Manufacturer
   10.3 Thromboplastin/Instrument Interaction
   10.4 Components of INR Determination
11 Optimizing the Local PT/INR Test System
   11.1 Prothrombin Time
   11.2 Mean Normal Prothrombin Time
   11.3 Thromboplastin Reagent With a Generic ISI
   11.4 Thromboplastin Reagent With an Instrument/
        Reagent-Specific ISI
   11.5 Use of Good Laboratory Practices
12 Recommendations for Verification of the Local Test
   System
   12.1 Verification of INR Results
13 Local System Calibration
   13.1 General Guidelines for the Use of Certified
        Plasmas
   13.2 Procedure for Calculating Local ISI
   13.3 Procedure for Establishing Direct INR (Locally)
   13.4 Interpretation of Patient Test Results
References
Appendix A. Determination of the Geometric Mean Normal
            Prothrombin Time (MNPT)
Appendix B. Calculations for Local ISI Determination and
            Direct INR Calibration Line
Appendix C. INR Verification, ISI Calibration, and Direct
            INR Calibration Line Preparation Using Certified
            Plasmas
Summary of Consensus/Delegate Comments and Subcommittee Responses
The Quality System Approach
Related CLSI/NCCLS Publications

Specifies the use of certified plasmas to enhance performance of the prothrombin time (PT)/International Normalized Ratio (INR) system test.

CLSI document H54 reviews limitations of the INR system and provides a rationale for performing localPT/INR verification with recommendations as to when calibration may be indicated.