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Thrombin Time Blood Test

Last updated Nov. 14, 2018

Approved by: Maulik P. Purohit MD, MPH

The Thrombin Time Blood Test is carried out by adding large amounts of thrombin to a sample of blood that has been stabilized by anticoagulant.

What are the other Names for this Test? (Equivalent Terms)

  • Thrombin Clotting Time Blood Test
  • TT Blood Test 

What is Thrombin Time Blood Test? (Background Information)

  • Thrombin is an enzyme that forms blood clots. It does this by converting a soluble protein, called fibrinogen, to its insoluble form, fibrin. The fibrin proteins then coalesce into a blood clot
  • Thrombin is kept in an inactive form called fibrinogen. This is to ensure that it is only activated, when injury necessitates the formation of a clot. It is a regulatory measure to prevent thrombosis, or blood clotting within the blood vessels
  • Fibrinogen is activated by the convergence of two clotting pathways. These are the intrinsic and extrinsic pathways. They are initiated by different parts of the body after an external insult to bodily tissues:
    • The intrinsic pathway begins in the blood with the activation of already circulating proenzymes
    • The extrinsic pathway begins in the blood vessel, with the secretion of protein factors by damaged cells lining the vessel
  • The extrinsic pathway is the first to activate. Damaged vessels expose underlying collagen and secrete protein factors. The intrinsic pathway then reinforces the extrinsic pathway and provides longer-lasting clotting effects
  • Each pathway utilizes specific factors that are made in the liver. In addition, calcium and vitamin K are essential to both pathways
  • The Thrombin Time Blood Test is a test to assess the function of fibrinogen. It is used to investigate clotting disorders for deficiencies (quantitative issues) or defects (qualitative issues) in prothrombin
  • The Thrombin Time Blood Test is carried out by adding large amounts of thrombin to a sample of blood that has been stabilized by anticoagulant. The time it takes for a clot to form is measured and compared to a standard

What are the Clinical Indications for performing the Thrombin Time Blood Test?

Following are the clinical indications for performing the Thrombin Time Blood Test:

  • Chronic anemia
  • Excessive bleeding
  • Monitoring anticoagulant therapy
  • As a follow-up to primary coagulation tests
  • To assess clotting ability before surgery 

How is the Specimen Collected for Thrombin Time Blood Test?

Following is the specimen collection process for Thrombin Time Blood Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: Inform your healthcare provider, if you are taking any anticoagulants. The test has to be performed, prior to taking such medications. 

What is the Significance of the Thrombin Time Blood Test Result?

The significance of Thrombin Time Blood Test is explained:

  • Prolonged thrombin time may indicate:
    • Liver disorder
    • Bone marrow disorder
    • Vitamin K deficiency
    • The individual is on anticoagulant therapy
    • Collagen disorder
    • Disseminated intravascular coagulation (DIC)
    • Cancer
    • Chronic pancreatitis
    • Toxic shock syndrome
    • Lupus anticoagulants
  • Accelerated prothrombin time may indicate:
    • Predisposition to clot formation within blood vessels (thrombosis)
    • Blockage of blood flow (embolism)
    • Tissue damage due to lack of blood flow (infarction)
    • Multiple myeloma 

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario. 

Additional and Relevant Useful Information:

The Thrombin Time Blood Test is often performed after primary coagulation tests, which include:

  • Partial thromboplastin time (PTT) test, which measures the integrity of the intrinsic and common pathways
  • Prothrombin time (PT) test, which measures the integrity of the extrinsic and common pathways 

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Oct. 18, 2014
Last updated: Nov. 14, 2018