What is the TT test for measuring thrombin time

Thrombin time measurement TT is mainly used to evaluate fibrinogen function and fibrinolytic system status, and is one of the important indicators for judging coagulation dysfunction. TT prolongation may indicate fibrinogen deficiency, abnormal fibrinogen, heparin therapy, or the presence of anticoagulant interference.

Thrombin time measurement involves adding a standard amount of thrombin to the plasma and observing the time required for fibrin formation. The reference value for TT in healthy individuals is usually 14-21 seconds, and the results are influenced by fibrinogen concentration, structure, and anticoagulant substances. When the fibrinogen content is less than 1 gram per liter, TT will be significantly prolonged. Abnormal changes in the molecular structure of fibrinogen can also hinder the formation of fibrin oligomers, leading to prolonged TT. Heparin and its analogues enhance antithrombin activity, inhibit thrombin, and increase TT detection values. Circulating anticoagulant substances such as antithrombin antibodies produced by certain autoimmune diseases and monoclonal immunoglobulin produced by multiple myeloma can interfere with the action of thrombin and prolong TT.

TT testing requires a comprehensive judgment based on indicators such as activated partial thromboplastin time (APTT) and prothrombin time (PT). When TT is simply prolonged while other indicators are normal, abnormal fibrinogen or the presence of specific anticoagulant substances should be considered. If TT and APTT are prolonged simultaneously, it indicates a lack of heparinization or common pathway coagulation factors. Clinically, it is commonly seen in advanced disseminated intravascular coagulation (DIC), severe liver disease, and other conditions. For patients receiving heparin treatment, TT can be used to monitor anticoagulant efficacy, but attention should be paid to the proper use of heparin neutralizing agents during testing.

Before conducting TT testing, avoid vigorous exercise and a high-fat diet. When collecting blood, ensure that it hits the nail on the head to avoid mixing tissue fluid. It is recommended to inform the doctor in advance when taking anticoagulants such as warfarin, and women during menstruation are advised to avoid physiological examinations. If the test results are abnormal, further supplementary examinations such as fibrinogen quantification, heparin concentration determination, or lupus anticoagulant screening should be performed. In daily life, attention should be paid to avoiding external injuries. If there is unexplained bruising or bleeding tendency, seek medical attention promptly and have coagulation function rechecked.