What Is a Thrombin Clotting Time Test?
It is one of the tests to check whether your blood is forming clots normally. It is a simple and rapid test to diagnose blood coagulation disorders. Whenever you encounter an injury, bleeding from the injury site is controlled and stopped with the formation of blood clots. Blood clot formation is called coagulation; it comprises cascades of events that require multiple blood components, including platelets, certain proteins called clotting factors, and enzymes. The last step of the coagulation cascade is the conversion of fibrinogen, a protein factor, into insoluble fibrin with the help of thrombin (a clotting factor that acts as an enzyme). These thread-like fibrins then crosslink with each other to form a stable fibrin meshwork, which attaches at the site of injury. Along with this, platelets adhere and form a stable clot that stops bleeding.
Thrombin time is used to diagnose fibrinogen's acquired or congenital deficiency or defect in its activity. Besides this, it is also a sensitive test to check the heparin contamination in the sample. It monitors the time required by the fibrinogen to turn into fibrin, noted in seconds; the reference range is usually below 20 seconds. Any problem in fibrinogen, either its low level or dysfunction that halts this conversion, results in inadequate clotting, leading to bleeding.
What Is The Test Used For?
This test is used for the evaluation of levels and activity of fibrinogen. It is used as a tool to investigate excessive and prolonged bleeding and inappropriate clot formation. The test is used to determine:
- Congenital or inherited conditions that cause decreased fibrinogen levels or dysfunctional fibrinogen synthesis.
- Liver diseases like hepatitis, cirrhosis and liver cancers lower fibrinogen synthesis as the liver forms it.
- Renal cancers (kidney cancers) and multiple myeloma (cancer of a type of white blood cell called plasma cell)
- Inflammatory conditions like ulcerative colitis and lupus, as fibrinogen is an acute phase reactant which acts as a marker and is raised significantly during acute inflammation.
- Formation of antibodies against fibrinogen if you had surgery in which fibrin glue is used from cow source.
- Disseminated intravascular coagulation (DIC) is a serious condition in which the body uses more fibrin leading to uncontrolled bleeding.
- For further evaluation of prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT). PT measures the effect of warfarin, while APTT is used to measure the effect of heparin.
- Suspecting contamination of blood samples with heparin or other anticoagulants.
- Certain medications also prolong the thrombin clotting time, including heparin, warfarin, and direct thrombin inhibitors (dabigatran).
- For monitoring and measuring the effectiveness of fibrinolytic therapy or thrombolytic therapy (dissolving or lysis of a blood clot).
This test is used along with other coagulation assays to look for the definite cause of abnormality in clot formation.
Why and When You Need To Get Tested?
Your healthcare provider may order this test alone or with a combination of other tests.
- If you notice excessive bleeding after minor injuries or recurrent bruising after minor traumas.
- If you are taking medicines including blood thinners (aspirin, dipyridamole), heparin and warfarin or direct thrombin inhibitors, etc.
- If you experience recurrent unexplained miscarriages, especially during early pregnancy or abnormal bleeding after delivery.
- If you have unnecessary bleeding after any kind of surgery or dental extraction.
What Type Of Sample Is Required?
A blood sample is required to perform this test. Your healthcare provider will use a small needle to draw blood from the vein of your hand or arm. A small amount of blood is obtained in a test tube or vial containing chemicals that prevent blood from clotting, and the sample is immediately transported to the laboratory. Samples that are more than 8 hours old may give inaccurate results.
Do You Need To Prepare For This Test?
Some medicines may alter blood clotting time and need to be stopped before running this test. Your healthcare provider will guide you on when to stop these medications. Be sure that you inform your healthcare practitioner about all your medications, including over-the-counter drugs and illegal drugs.
Is There Any Risk To This Test?
Since a needle is used, you may feel pain and sting at the site of the prick. Sometimes you experience bruises or bleeding, and very rarely, infections may occur. If you undergo excessive or prolonged bleeding from the prick site, you should immediately consult your healthcare provider.
What Does The Result Mean?
The test result is usually obtained between 12-48 hours. The reference range is usually 14 – 19 seconds, but it may differ for different laboratories. Also, separate reference ranges are used for infants.
- A longer thrombin clotting time suggests that more time is needed for the blood to form a clot, which means you may have low fibrinogen or dysfunctional fibrinogen is present that is not working properly as occurring in cases of DIC, malabsorption, and end-stage liver diseases. It can also be caused by certain blood-thinning medicines or heparin-like substances or clotting inhibitors, e.g., fibrin degradation products, direct thrombin inhibitors, etc. Moreover, antibodies formed against fibrinogen may destroy them and lower fibrinogen levels, altering the normal coagulation time.
- A shorter thrombin clotting time means your blood is clotting more quickly than normal, which may be caused by the increased level of proteins in your blood, like in the case of multiple myeloma, and amyloidosis may accelerate blood clot formation. Certain cancers that increase proteins that clot your blood and certain medicines like oral contraceptive pills and hormone therapies may also increase blood clotting.
If you have any concerns about test results, you should consult your healthcare provider.
- Reptilase time
- Prothrombin time (PT)
- Activated partial thromboplastin time (APTT)
- International normalization ratio (INR)
- Fibrinogen antigen assay
- Liver function test (LFTs)
- Lupus anticoagulant screen
- Antiphospholipid syndrome criteria penal
Frequently ordered together
Thrombin Clotting Time with Reflex to Mixing Studies
Prothrombin Time with INR