Department of Laboratory Medicine
University of Washington
 
Clinical assay interference and limitations

Warfarin Therapy

Prophylactic anticoagulation, for example: chronic therapy for patients with a history of DVT or pulmonary embolism but without acute or ongoing thrombosis.
Suggested Protime (PT): INR = 2 to 3

Full anticoagulation, for example: acute DVT or pulmonary embolism, prothetic heart valves or extensive artificial arterial or venous grafts.
Suggested Protime (PT): INR = 2.5 to 3.5

In some cases (e.g. thrombosis associated with lupus inhibitors and the antiphospholipid antibody syndrome), even higher INRs of 3.0 to 4.5 may be needed.

CRITICAL PT: INR greater than 5.0















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Created: February 28, 2002
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