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Primary Name Prothrombin Time/INR
Synonym Prothrombin time
Synonym Protime
Contraction PT/INR
Contraction INR
Contraction PT
UAB Procedure Number 2500100
CPT Code 85610
Specimen Collect one (1) blue-stopper tube (3.2% sodium citrate), filled to specified volume. Do not underfill or overfill.

Specimen Management Centrifuge blue-stopper tube within one (1) hour of collection, separate plasma and test or quick-freeze at -70°C.
Specimen Accepted Daily including weekends
Times Available All times
Test Performed All times
Available Stat? Yes
Description PT is performed to monitor oral anticoagulant therapy (Coumadin, warfarin) and to detect factor deficiencies of the extrinsic and common coagulation pathways.
Reference Interval Call lab for current reference range
Critical Value Call lab for current critical values.
Therapeutic Range *For warfarin monitoring following venous thromboembolism, myocardial infarction, atrial fibrillation or rheumatic heart disease: INR 2.0-3.0.
*For warfarin monitoring for those with mechanical heart valves: INR 2.5-3.5.
Follow-up Test PT mixing studies if prolonged in the absence of anticoagulation
Associated With Coagulation factor inhibitors
Associated With Bleeding disorders
Associated With Lupus anticoagulant
Associated With Coumadin (warfarin) therapy
Associated With Disseminated intravascular coagulation
Associated With Liver disease
Associated With Vitamin K deficiency

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