Geisinger Medical Laboratories Test Catalog

Order Display Name: Geisinger Epic Procedure Code Or ID CPT Code:  

THROMBIN TIME

ORDERING INFORMATION:
Geisinger Epic Procedure Code: LAB3152         Geisinger Epic ID: 7224

SPECIMEN COLLECTION
Specimen type:
 Platelet-free plasma
Preferred collection container:
Alternate Collection Container:
Other size blue-top (3.2% sodium citrate) tubes (e.g., 1.8 mL, 4.5 mL)
Specimen required:
1 mL aliquot plasma
Special notes:
  • If the patient’s hematocrit (HCT) is >55%, the volume of anticoagulant in the tube must be adjusted. Contact a performing location for sodium citrate adjusted tubes or instruction for how to adjust the sodium citrate.
  • When possible, use fresh venipuncture.
  • Avoid prolong tourniquet time (< 1 minute) and hemolysis during collection as this will alter results.
  • If indwelling catheter or butterfly collection device must be used, draw sample from a non-heparinized lumen or flush the line with 5 mL of saline and discard/use first 5-10 mL of blood for other purposes.
  • Tubes should be >90% filled.
  • Immediately mix gently after collection by inverting the tube end over end 5 to 6 times. Avoid vigorous mixing or additional inversion. Observe for the presence of clots and recollect if observed.
SPECIMEN PROCESSING
Specimen processing instructions:
Centrifuge specimen immediately at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. If plasma is icteric, lipemic or hemolyzed a lab comment should be generated to notify staff. Freeze upright in non-thaw freezer. 
Transport temperature:
 Frozen on dry ice
Specimen stability:
 Room temperature (whole blood): 4 hours
Room temperature (plasma off cells): 8 hours
Frozen (plasma) -20°C: 2 weeks
Frozen (plasma) -70°C: 6 months
Rejection criteria:
 Clotted specimen. Overfilled or underfilled tubes. Stability limits exceeded. HCT >55. HCT > 55 requires rejection, reorder in LIS, and recollection with proper adjustment of anticoagulant. Indications of thaw in transit are sample on slant in aliquot tube or in lid of tube. These samples will be run but will receive a comment of interpret results with caution as thawing suspected.
TEST DETAILS
Reference interval:
 14.7 to 19.6 seconds
Additional information:
 Anticoagulation Impact on Coagulation Tests
CPT code(s):
 85670
Note: The billing party has sole responsibility for CPT coding.  Any questions regarding coding should be directed to the payer being billed.  The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only.
Test includes:
 Thrombin time
Methodology:
Mechanical clot-based
Synonyms:
TT, thrombin clot time
Clinical significance:
The thrombin time is typically prolonged when fibrinogen is less than 100 mg/dL or in the presence of antithrombotic substances including fibrin degradation products, paraproteins, or anticoagulation with either heparin or direct thrombin inhibitors. It can also be prolonged if the fibrinogen is biochemically abnormal or nonfunctional (dysfibrinogenmia).

Thrombin time is typically used in conjunction with fibrinogen activity, fibrinogen antigen, and replitase time assays to determine if the patient has hypofibrinogenemia (low amount of fibrinogen), dysfibrinogenemia, or the plasma contains anticoagulation with either heparin or a direct thrombin inhibitor.

Thrombin time is part of the PT/APTT mixing study panel, lupus anticoagulant profile, and thrombosis profile to determine whether anticoagulation is present.

Doctoral Director(s:)
Michelle Grant DO    
Review Date: 03/28/2023

Performing Locations

Geisinger Medical Center

Performing laboratory: Coagulation
Technical Lead: Margaret Knowles-Tuchman
Frequency: Daily, all shifts
Performed STAT? Yes

Geisinger Wyoming Valley Medical Center

Performing laboratory: ATL+
Technical Lead: Julia Bell    
Frequency: Daily, all shifts    
Performed STAT? Yes

Geisinger Community Medical Center

Performing laboratory: Hematology
Technical Lead: Robert Furcon  
Frequency: Daily    
Performed STAT? Yes
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