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Poor correlation of supratherapeutic international normalised ratio and vitamin K‐dependent procoagulant factor levels during warfarin therapy
Author(s) -
Sarode Ravindra,
Rawal Ajay,
Lee Ray,
Shen YuMin,
Frenkel Eugene P
Publication year - 2006
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.2005.05917.x
Subject(s) - warfarin , medicine , prothrombin time , vitamin k , partial thromboplastin time , hypoprothrombinemia , vitamin , vitamin k deficiency , prospective cohort study , gastroenterology , coagulation , atrial fibrillation
Summary Patients with a supratherapeutic international normalised ratio (ST‐INR) are at risk for bleeding. ST‐INR is corrected by withholding warfarin therapy and often by supplementing vitamin K or providing vitamin K‐dependent factors; the exact therapeutic decision is based on the extent of the prolonged INR. Currently, ST‐INRs are frequently observed in clinical practice due to the use of sensitive recombinant tissue thromboplastin reagents and automation. However, there are scant data correlating an ST‐INR with various vitamin K‐dependent factors. This prospective cohort study, set in a large tertiary care teaching hospital for the University of Texas Southwestern Medical Center at Dallas, defined the relationship between ST‐INR (>5·0) and measured vitamin K‐dependent procoagulant factors. Prothrombin time, INR and vitamin K‐dependent factors II, VII, IX and X were measured in 78 patients with an INR > 5·0 (ST‐INR) who were on warfarin therapy for more than 2 months. There was no significant relationship between the ST‐INR and levels of important vitamin K‐dependent factors II and X. These data support the recent guidelines that the management of an INR > 5·0 should be driven by the clinical determinants rather than specific INR values per se .