Prothrombin Fragment 1.2

Optimal Result: 41 - 372 pmol/L.

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.


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.

What does it mean if your Prothrombin Fragment 1.2 result is too high?

Elevated levels of prothrombin fragment 1 + 2 indicate a high risk of thrombosis.

Prothrombin fragment 1 + 2 (F1 + 2) is considered to be useful for the diagnosis of thrombosis. However, the evidence for a diagnosis of thrombosis by F1 + 2 is still not well established. The plasma concentrations of F1 + 2, soluble fibrin, D-dimer, and thrombin-antithrombin complex were measured in 694 patients suspected of having thrombosis and then were correlated with thrombosis.

Plasma concentrations of F1 + 2, soluble fibrin, D-dimer, and thrombin-antithrombin complex were significantly higher in patients with thrombosis than those without thrombosis. 


Elevated levels of Prothrombin Fragment 1.2 in the blood are clinically significant as they indicate increased thrombin generation, which is a key part of the blood clotting process. Prothrombin Fragment 1.2 is a specific peptide that is released when prothrombin is converted to thrombin, an essential step in the coagulation cascade. Elevated levels can be observed in several conditions:

1. Hypercoagulable States: High levels of Prothrombin Fragment 1.2 are often seen in hypercoagulable states, where there's an increased tendency for blood clot formation. This can occur in various disorders, including certain genetic conditions like Factor V Leiden mutation, prothrombin gene mutation, and other acquired conditions like antiphospholipid syndrome.

2. Active Thrombosis: Elevated levels can be indicative of active thrombosis, such as deep vein thrombosis (DVT) or pulmonary embolism (PE). It suggests that the clotting process is actively occurring.

3. Cardiovascular Diseases: In patients with cardiovascular diseases like atrial fibrillation or after a myocardial infarction, increased levels may reflect a heightened state of coagulation.

4. Cancer: Some types of cancers can induce a hypercoagulable state, leading to elevated levels of Prothrombin Fragment 1.2.

5. Use of Certain Medications: Medications like oral contraceptives or hormone replacement therapy, which can increase the risk of blood clots, may also elevate these levels.

It's important to interpret elevated levels of Prothrombin Fragment 1.2 in the context of the patient's overall health, medical history, and other laboratory findings, as they are not specific to a single condition but rather indicate an increased coagulation activity in the body. This can necessitate further investigation and management to address the underlying cause and to mitigate the risk of thrombotic complications.

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