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|25000:PROTHROMBIN TIME (PT)|
|Alias Names:||PT / Protime, INR / Coumadin/Warfarin Monitoring|
|Methodology:||Mechanical Clot Detection|
|Specimen Collection Details|
|Collection:||One 4.5 mL light blue top tube (sodium citrate). Collect by careful venipuncture to avoid tissue contamination or hemolysis. Do not use needles smaller than 23 gauge. Fill tube to maximum draw (at least 75% full). Mix by gentle inversion. If patient hematocrit is >55%, collection into an adjusted volume of anticoagulant is required. Call PeaceHealth Laboratories Coagulation Department (541.687.2134 x4665) for instructions.|
|Handling:||Refrigerate and keep capped in original tube if specimen will be received at the laboratory within 24 hours. If not, centrifuge to produce platelet-poor plasma (at least 1700 X G for 15 minutes) and transfer the top 2/3 of the plasma with a plastic pipette into a plastic vial, and freeze immediately. Label with name, test and ”citrate.” If multiple tests are ordered, freeze a separate aliquot for each test. Send to PeaceHealth Laboratories within 7 days. NOTE: The Protime test cannot be added to a tube which has been opened for longer than 4 hours.|
|Stability:||Unopened tube stable 24 hours refrigerated.
Opened tube 4 hours ambient, 4 hours refrigerated, or 7 days frozen.
|Standard Volume:||4.5 mL whole blood or 2 mL plasma.|
|Minimum Volume:||1.8 mL whole blood or 0.5 mL plasma.|
|Transport:||Original tube refrigerated if within 24 hours, or citrated plasma frozen on dry ice in a Styrofoam container.|
|Comments:||For hospitalized patients, indicate coumadin or heparin therapy. When drawing from heparin lines, withdraw slowly and discard at least 10 mL of blood to clear before drawing specimen. Heparin interferes with most clotting assays.
See also: Coagulation Study, Presurgical Panel 1 (25440), Presurgical Panel 2 (25470), Coagulation Study, Bleeding Disorder Evaluation (25800), Coagulation Study, D.I.C. Screen (25520) , or Coagulation Study, Prolonged Prothrombin Time (PT) Evaluation (25720) .
|Rejection Criteria:||Serum; visible fibrin; moderate to marked hemolysis; improperly filled tube or tube uncapped for longer than 4 hours.|
|Reference range for Prothrombin Time seconds varies with reagent lot number and is included in the report. Prothrombin Time INR values are not affected by reagent changes and reference ranges appear below.|
DVT, PE. Atrial Fibrillation,
St Judes valve, aortic position
|Most mechanical valves, recurrent thrombosis||2.5-3.5|