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Thrombin Time

TT

Test Codes

EPIC: LAB1230581

Department

Coagulation

Instructions

Specimens with hematocrit values greater than 55% must have anticoagulant adjusted. Specimens must be re-collected using a specified whole blood to sodium citrate ratio. Contact the performing Laboratory for specific instructions.

Specimen Collection Criteria

Collect: One Light Blue-top 3.2% Sodium Citrate tube.

TUBE MUST BE FULL.

Physician Office/Draw Specimen Preparation

For optimal results, maintain whole blood specimen at room temperature (20-26°C or 68-78.8°F) prior to transport. Transport whole blood to the Laboratory within 4 hours of collection. If transport within 4 hours is not possible, the following procedure must be followed for accurate results:

1. Centrifuge the capped tube at 1500 x g for 15 minutes.
2. Transfer plasma with a plastic pipette into a plastic polypropylene centrifuge tube, cap and centrifuge an additional 15 minutes at 1500 x g to obtain platelet poor plasma (PPP) which has a platelet count less than 10 bil/L. Plasma with a platelet count of less than 10 bil/L is critical for accurate results.
3. Immediately remove only the top two-thirds of the PPP and transfer it into a screw cap, 5 ml, 75 x 13 mm, round base, polypropylene tube.  
4. Freeze (-20°C/-4°F or below) the PPP immediately.
5. Transport frozen on DRY ICE. Specimen must remain frozen during transport. 

Preparation for Courier Transport

Transport: Whole blood at room temperature (20-25°C or 68-77°F), or plasma obtained through the process listed above, frozen (-20°C/-4°F or below).

Rejection Criteria

• Glass tubes and 3.8% Sodium Citrate tubes.
• Specimens that are clotted or grossly hemolyzed.
• Inappropriate specimen volume.
• Thawed or partially thawed specimens.

In-Lab Processing

Whole blood specimens must be processed as follows upon receipt in the Laboratory:

1. Centrifuge the capped tube at 1500 x g for 15 minutes.
2. Transfer plasma with a plastic pipette into a plastic polypropylene centrifuge tube, cap and centrifuge an additional 15 minutes at 1500 x g to obtain platelet poor plasma (PPP) which has a platelet count less than 10 bil/L. Plasma with a platelet count of less than 10 bil/L is critical for accurate results.
3. Immediately remove only the top two-thirds of the PPP and transfer it into a plastic tube.

4. Test or freeze specimen according to lab protocol.

Storage

Specimen Stability for Testing:

Whole Blood
Room Temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Platelet Poor Plasma (PPP)
Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): 30 days

Specimen Storage in Department Prior to Disposal:

Room Temperature (20-26°C or 68-78.8°F): 5 days
Refrigerated (2-8°C or 36-46°F): 5 days
Frozen (-20°C/-4°F or below): 30 days

Laboratory

Royal Oak Coagulation Laboratory

Performed

Sunday – Saturday, 24 hours a day.
STAT results available within 30 minutes of receipt in the Laboratory.
Routine results available within 2 hours of receipt in the Laboratory.

Reference Range

Normal Range: 16-25 seconds.

Test Methodology

Photo-Optical Clot Detection (IL ACL-TOP Series)

Interpretation

Prolonged thrombin time may be seen in hepatic disease, DIC, afibrinogenemia, dysfibrinogenemia, systemic lupus erythematosus and macroglobulinemia.

Clinical Utility

The final stages of the clotting process, the conversion of fibrinogen to fibrin, may be tested by measuring the thrombin time. The mechanism responsible for the abnormal thrombin time is due to qualitative alterations in fibrinogen or to decreased concentration of fibrinogen. In other cases, an endogenous or exogenous circulating anticoagulant such as heparin, heparin-like substances, or direct thrombin inhibitors may lengthen the thrombin time.

CPT Codes

85670

LOINC: 3243-3

Contacts

Last Updated

8/15/2024