Blood Clotting / Coagulation Tests: What They Measure, Normal Ranges & What Results Mean

12 biomarkers Peer-reviewed

Biomarkers in this category

12 biomarkers · optimal ranges shown

Antithrombin Activity (ATIII)

Antithrombin Activity (ATIII), also known as AT III or AT 3, is a key biomarker that measures how effectively antithrombin, a natural anticoagulant protein, functions in the blood. Antithrombin is crucial for regulating clot formation by inhibiting thrombin and clotting factors like factor Xa, helping maintain a balance between clotting and bleeding. Normal ATIII activity ranges from 80% to 120%. A decrease in ATIII activity may indicate inherited or acquired deficiencies and is often linked to conditions like deep vein thrombosis (DVT), pulmonary embolism, liver disease, nephrotic syndrome, disseminated intravascular coagulation (DIC), or vitamin K deficiency. While elevated ATIII activity is less common, it may occur during inflammation, certain stages of pregnancy, or after antithrombin supplementation or anticoagulant therapy. Testing for antithrombin activity is vital for diagnosing clotting disorders, monitoring anticoagulant therapies (e.g., heparin), and evaluating overall hemostatic function. It is often performed alongside other tests, such as Protein C and S Activity, aPTT, PT/INR, and Factor V Leiden, to assess thrombophilia risk comprehensively. The test involves a blood draw, with plasma used as the specimen. Emerging research highlights that certain demographic factors, such as Hispanic ethnicity, may influence ATIII activity in clinical contexts. This underscores the importance of considering patient-specific characteristics when interpreting test results.

Optimal range 76 – 128 % Learn more
Prothrombin Fragment 1.2

The test is useful to assess ongoing coagulation activation as may occur in thrombosis or DIC. When prothrombin is converted to thrombin, the prothrombin fragment 1.2 is released from prothrombin. The conversion of prothrombin to thrombin is a key event in the coagulation of blood. Prothrombin fragment 1.2 is an activation peptide released from prothrombin during thrombin formation. Activation of prothrombin takes place in the presence of factor Xa, factor Va, calcium ions and a phospholipid suface (platelets). Prothrombin fragment F1+2 may be generated during thrombin formation in two ways. Either prothrombin is cleaved to prethrombin 2 and prothrombin fragment F1+2. Subsequently prethrombin 2 is further cleaved at one position to yield active thrombin. The alternative way of activation is that prothrombin is cleaved to meizothrombin still containing the prothrombin fragment F1+2, and is then processed to thrombin, liberating the prothrombin fragment F1+2. The prothrombin fragment F1+2 may further be cleaved by thrombin to fragments F1 and F2. Prothrombin Fragment 1+2 [F1+2] is an activation peptide that is generated when Prothrombin [Factor II] is converted to Thrombin. Prothrombin is activated to Thrombin [Factor IIa] by a membrane-bound enzyme complex - Prothrombinase and which is assembled through reversible interactions between Factor Xa and Factor Va on membranes containing Phosphatidylserine – a Phospholipid. References: Ota S, Wada H, Abe Y, Yamada E, Sakaguchi A, Nishioka J, Hatada T, Ishikura K, Yamada N, Sudo A, Uchida A, Nobori T. Elevated levels of prothrombin fragment 1 + 2 indicate high risk of thrombosis. Clin Appl Thromb Hemost. 2008 Jul;14(3):279-85. doi: 10.1177/1076029607309176. Epub 2007 Dec 26. PMID: 18160575. Haeberli, A. (1999). Prothrombin fragment F1+2. In: Jespersen, J., Bertina, R.M., Haverkate, F. (eds) Laboratory Techniques in Thrombosis — a Manual. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-4722-4_23

Optimal range 41 – 372 pmol/L Learn more
Thrombin Antithrombin Complex

The Thrombin Antithrombin Complex (TAT) marker is an important blood test used to evaluate the balance between clot formation and dissolution in the body, which is crucial for understanding certain blood clotting disorders. Thrombin is a protein that plays a central role in the blood clotting process, helping to convert fibrinogen into fibrin, which forms the basic structure of a blood clot. Antithrombin, on the other hand, is a protein that helps regulate blood clot formation by inhibiting thrombin and other enzymes involved in the coagulation process. When thrombin is generated in the bloodstream, it binds to antithrombin, forming the thrombin-antithrombin complex. Measuring the levels of this complex can provide valuable information about the activation of the coagulation system and the body's response to it. High levels of the TAT complex may indicate an active clotting process, which can be seen in conditions such as deep vein thrombosis, pulmonary embolism, disseminated intravascular coagulation, and in patients with a high risk of clot formation. It can also be elevated in certain surgeries or medical conditions that predispose to clotting. Understanding the levels of TAT can help healthcare providers diagnose and manage conditions related to abnormal clotting. By integrating this marker into a comprehensive evaluation, it helps in guiding treatment decisions, such as the need for anticoagulant therapy, which aims to prevent or reduce the formation of harmful blood clots.

Optimal range 0 – 4.3 ng/mL Learn more
Thrombin time

The thrombin time (TT) is a blood test that measures the time it takes for a clot to form in the plasma of a blood sample containing anticoagulant, after an excess of thrombin has been added. It is used to diagnose blood coagulation disorders and to assess the effectiveness of fibrinolytic therapy. Blood clotting is an important step in healing from an injury, such as a cut. Forming a blood clot is a complicated process. It involves many blood components that must interact in a specific order. Thrombin time is a measure of how long the blood's plasma, or the liquid portion of the blood, takes to form a clot. This test gives information about how well one particular blood component called fibrinogen is working. A normal thrombin time is 11.3 to 18.5 seconds.

Optimal range 11.3 – 18.5 seconds Learn more