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Test Code TT (TT) Thrombin Time

Additional Codes

 Test ID

TT

EPIC Test ID

LAB324

Specimen Requirements

Container/Tube Type: 

Light Blue (Citrate)

Collection Information: 

Collect one full blue top tube

Transport Information: 

  1. Spin down, remove plasma, spin plasma again, and place 1 mL of platelet-poor plasma in plastic vial. (Glass vial is not acceptable.) Note: Double-centrifuged specimens are critical for accurate results as platelet contamination may cause spurious results. 
  2. Freeze specimen immediately at ≤ -40° C, if possible.
  3. Send specimen frozen.

Note: Each coagulation assay requested should have its own vial.

Platelet Poor Plasma
Centrifuge Specimen

Recommended centrifuge speed is 1500 x G for at least 15 minutes. Be careful that the tubes are evenly balanced when placing them into the centrifuge. When the centrifuge stops, carefully remove and rack tubes. Be aware that an unbalanced centrifugation, speed too slow, or centrifugation for too short of a spin time may all lead to an increase number of cells in the plasma which could contribute to a clotted specimen or erroneous results.
Remove Plasma
To remove plasma, start from the top, gently draw specimen into pipette as you go further down tube. Leaving approximately 0.5mL of plasma will insure that you do not disturb the buffy coat and cell layer.
Second Spin
Plasma separated from cells goes back into the centrifuge for a second spin. Balance and centrifuge the tubes. Failure to perform a second spin will result in plasma containing too many platelets which interfere with some coagulation testing and is a contributing factor for a clotted specimen.
Transfer Plasma to Aliquot Tubes
Pipette plasma from second spin tube into labeled aliquot tubes without disturbing the bottom 0.5mL.
Specimen Storage
Promptly freeze specimens after processing.

Minimum Sample Volume

0.5 mL of plasma (approximately 1.0 mL of whole blood based upon a normal patient's hematocrit)

Specimen Stability

Refrigerated Stability: 

NOT Acceptable

Frozen Stability: 

30 days

Ambient Stability: 

2 hours

Report Availibility

Performed: 

Daily, 24 hours

Methodology

Clot-Based Assay

Unacceptable Conditions

Hemolyzed or lipemic specimens.