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Test Name:
Thrombin Clotting Time
- SBMF No:
25235 - Performance Lab Name:
Hem-Coag - Test Mnemonic:
TCT - ABN:
Not required - CPT Code:
85670 - LOINC Code:
3243-3 - Also Known As:
TCT
Thrombin Time - Spec Type:
Platelet-poor plasma (PPP) - Spec Container:
Light blue top (3.2% buffered sodium citrate) tube - Pref Vol:
2.0 mL (Two aliquots, 1.0 mL each) - Fasting:
No - Patient Prep:
Collect prior to initiation of anticoagulant therapy - Spec Collect:
- Routine venipuncture
- • NOTE: Traumatic puncture invalidates sample for coagulation studies and necessitates recollection
• Observe proper collection order for coagulation tests; collect tubes for coagulation studies prior to collecting tubes containing clot activators, additives, or anticoagulants
• Fill light blue top tube to stated tube volume
• If coagulation study is only test ordered, collect 1.0 to 2.0 mL blood into tube for discard, then collect light blue top coagulation study tube(s)
• If multiple coagulation studies are requested, submit additional samples for each coagulation test
• Immediately after collection, gently invert tube to mix
- Spec Process:
- Separate plasma from cells immediately
- • Promptly centrifuge 15 minutes
• Carefully transfer plasma portion of sample to separate plastic tube using plastic pipette
• NOTE: Buffy coat layer of sample must be avoided
• Centrifuge transferred plasma sample again to produce platelet-poor plasma (PPP)
• Use second plastic pipette to carefully transfer PPP sample into plastic aliquot tubes
• Immediately freeze PPP samples
- Spec Store Transport:
Frozen - Spec Stability:
4 hours room temperature (20-30°C)
2 weeks frozen (-20°C) – Do not use frost-free units that undergo repeated freeze/thaw cycles - Spec Reject:
Citrate tube underfilled
Sample clotted or hemolyzed
Plasma not frozen within 4 hours of collection - Spec Remarks:
Platelet-poor plasma (PPP) samples obtained by double centrifugation are critical for accurate coagulation studies as platelet contamination may cause spurious results - Methodology:
Clot Detection - Use:
Used in determination of severe hypofibrinogenemia, dysfibrinogenemia, and presence of heparin-like anticoagulant
Also useful in diagnosis and monitoring of disseminated intravascular coagulation (DIC) and fibrinolysis - Clinical Significance:
The thrombin clotting time (TCT) procedure is a rapid test method that is useful in the evaluation of hemostasis and thrombosis. TCT is a screening test for presence of sufficient amount of functional (clottable) fibrinogen. A standard concentration of thrombin is added to undiluted plasma and the clotting time is measured. TCT is used in determination of severe hypofibrinogenemia, dysfibrinogenemia, and presence of heparin-like anticoagulants. It is also useful in diagnosis and monitoring of disseminated intravascular coagulation (DIC) and fibrinolysis.
The test is based on conversion of functional fibrinogen to fibrin upon addition of thrombin to plasma.
The determination of the thrombin time using BC Thrombin Reagent is suitable for: 1) monitoring heparin therapy using unfractionated heparin; 2) fibrinolysis therapy; 3) screening for disorders of fibrin formation, and 4) in cases of suspected severe fibrinogen deficiency states, and differentiating between a heparin-induced prolongation of the thrombin time and fibrin formation disorders.
- Reference Range:
Less than 21 seconds - Additional Test Info:
Prolongation of TCT may be observed in plasma with low fibrinogen levels (less than 60-80 mg/dL) or extremely elevated high fibrinogen levels (greater than 800 mg/dL), presence of fibrin degradation product (FDP), and heparin. TCT may be used to monitor heparin therapy, but results may be unreliable when presence of hypofibrinogenemia and fibrin breakdown products generated by a process of DIC. The desirable therapeutic range for heparin therapy and thrombolytic therapy using streptokinase or urokinase is two- to fourfold of the upper reference limit. - Day Run:
Mon-Fri - Time Run:
7:00 am - Time Reported:
5:00 pm - Test Type:
COAGULATION
