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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 |
13.2-15.2 seconds/INR 1.0 |
| Critical Value |
> 50 seconds |
| Therapeutic Range |
*For oral anticoagulant monitoring following venous thromboembolism, myocardial infarction, atrial fibrillation or rheumatic heart disease: INR 2.0-3.0.
*For oral anticoagulant 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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