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Measurement of thrombin time (TT) is one of the tests performed as part of the diagnosis of blood coagulation disorders. It is used to assess the time of transformation of fibrinogen into insoluble fibrin, which is a key protein in the process of clot formation. When is thrombin time analyzed and what are the abnormalities?
What is thrombin time?
Thrombin time (TT) is a diagnostic test that allows a partial assessment of the coagulation system. On the basis of TT, it can be seen how long it takes for the final stage of blood clotting, i.e. the conversion of fibrinogen to fibrin, to take place.
Fibrinogen is a soluble protein in the blood plasma that is formed in the liver. Under the influence of coagulation factor IIa, i.e. thrombin, fibrinogen is transformed into insoluble fibrin (fibrin). It is fibrin that takes the form of a protein network of fibers in which white, red and platelet cells are trapped to form a clot.
This is why thrombin time is an important parameter that is measured before surgery – it tells you how long bleeding can take before the body is able to start forming a clot. This is not the only circumstance for which the TT test is commissioned.
When is thrombin time measured?
On the result thrombin time measurement influenced by various factors, including the concentration of fibrinogen and its functioning, the polymerization processes and stabilization of fibrin, as well as the intake of anticoagulants. Unlike prothrombin time, TT is not influenced by other processes related to the activation of a series of clotting reactions.
Study of thrombin time is performed:
- in the event of bleeding of unknown origin;
- upon suspicion of a coagulation disorder in a patient;
- at suspicion of liver or kidney disease;
- to monitor treatments that require the administration of drugs that affect clotting;
- checks to make sure that the plasma sample has not been contaminated with heparin.
Thrombin time – the course of the study
A small blood sample is enough to determine the thrombotic time. Standardized withdrawals performed with precautionary measures are safe, but increased monitoring is important in those with bleeding disorders. In these cases, you may experience prolonged bleeding and sometimes bruise.
- The material for the study of thrombin time is plasma.
- Preparation for the blood test: The patient goes to the test on an empty stomach (the last meal should be eaten at least 8 hours before the collection), should be asleep, it is recommended to rest 15 minutes before blood donation. Before the TT examination, it is recommended to give up physical activity. People taking medications should consult their physician regarding possible effects on results.
- Course of TT test: A blood sample is taken from the patient once from a vein in the arm, for which a sterile syringe with a thin needle is used. After the puncture is performed and the sample is obtained, the patient is given a gauze pad with which to apply pressure to the bleeding site. The collected blood is sent to the laboratory, where thrombin is added to it, and then the chastrombin is assessed.
- The waiting time for the test results is on average one day.
You should go to the doctor who ordered the test with the results of the thrombin time test. It will compare the results with the results of other tests and your symptoms, which will allow you to correctly diagnose any disease or control your treatment.
The norm of thrombin time and deviations
The correct value for thrombin time should be between 12 and 24 seconds, but the norm may vary depending on the laboratory. If the TT result is abnormal, the physician may refer the patient to a batroxobin time test.
If the TT study shows that cand the thrombin is elongated, this may indicate:
- condition after surgery in which bovine thrombin was used;
- kidney failure accompanied by uremia, i.e. the presence of toxic metabolic products in the body;
- diseases affecting the liver parenchyma that lead to a disturbance in the synthesis of fibrinogen and prothrombin; an example would be cirrhosis of the liver;
- previous treatment with asparaginase or heparin;
- deficiency of fibrinogen despite the correct structure of molecules (hypofibrinogenemia);
- absence of fibrinogen, i.e. fibrinogenemia;
- fibrinogen dysfunction resulting from its abnormal structure (dysfibrinogenemia);
- syndrome of disseminated intravascular coagulation (DIC), in which excessive consumption of fibrinogen is observed;
- disease from the group of monoclonal gammapathies.
Do you need interpretation of test results? Are you worried about your symptoms? Contact your doctor. Make an online teleconsultation with your family doctor at haloDoctor.pl to get answers to your questions.
Other clotting tests
In order to obtain complete information about the patient’s blood clotting process, more detailed tests are necessary. It is a comprehensive coagulation test coagulogram. Its composition, apart from thrombin time, may also include prothrombin time (PT), coallion-kephalin time (APTT), batroxobin time, concentration of fibrinogen and antithrombin III.