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|27120:THROMBIN TIME (TT)|
|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 fluid contamination or hemolysis. Do not use needles smaller than 23 gauge. Fill tube to maximum draw, at least 90% full. Mix by gentle inversion.|
|Handling:||Due to short stability, specimen must either be sent STAT to arrive at the laboratory within 2 hours, or sent frozen. If STAT, refrigerate and keep capped in the original tube. For standard delivery, centrifuge to produce platelet poor plasma (at least 1700 x G for 15 minutes) and with a plastic pipette, transfer to a plastic vial. Freeze immediately and label with patient name, I.D. number, test, and “citrated plasma.” Send to the laboratory within 7 days. If multiple tests are ordered, freeze a separate aliquot for this test.|
|Stability:||2 hours refrigerated, or 7 days frozen. Unstable ambient.|
|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 STAT, or citrated plasma frozen on dry ice.|
|Comments:||This test is a sensitive screen for fibrinogen function and heparin contamination. Special care must be taken with this test to avoid heparin contamination as a result of collection from heparin lines. If possible, avoid drawing this test from heparin lines. If necessary, clear the line by slowly drawing and discarding 10 mL of blood before drawing the specimen for testing. Draw the blue top tube last if multiple tests are being drawn.|
|Rejection Criteria:||Visible fibrin; moderate to marked hemolysis; specimen received in laboratory beyond stated stability.|
|Varies with reagent lot number. Current reference range included with report.
The Thrombin Time is a sensitive screen for fibrinogen function, i.e., dysfibrinogenemia, and the presence of heparin.