Oral Anticoagulant Monitoring by Laboratory or Near-Patient Testing: What a Clinician Should Be Aware Of

A. Tripodi, W. G M Breukink-Engbers, A. M H P Van den Besselaar

Research output: Contribution to journalArticle


Prothrombin time (PT) is the primary laboratory test for monitoring oral anticoagulant treatment but is influenced by preanalytical conditions and analytical variables, that is, thromboplastin reagents and instrumentation. Standardization and normalization of test results is mandatory. PT results should be transformed to International Normalized Ratio (INR) by calibration of the reagent/instrument system with International Reference standards according to World Health Organization guidelines. However, there is still uncertainty in the INR that is caused in part by calibration errors and in part by interaction between the PT reagent and various factors in the patient's specimen. These problems are highlighted in INR measurements performed with whole blood coagulation monitors. Each center should maintain an appropriate scheme of internal and external quality control for the laboratory INR measurement as well as the individual point-of-care coagulation monitors used by the center and patients for self-testing.

Original languageEnglish
Pages (from-to)243-254
Number of pages12
JournalSeminars in Vascular Medicine
Issue number3
Publication statusPublished - Aug 2003



  • International Normalized Ratio
  • Near-patient testing
  • Oral anticoagulation

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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