Prothrombin Fragment 1+2 Unit Converter

Prothrombin Fragment 1+2 (F1+2) is a small protein fragment released into the bloodstream when prothrombin (Factor II) is converted into thrombin, the enzyme that drives blood clot formation. Each time this conversion occurs, exactly one molecule of F1+2 is produced.

Because F1+2 is generated in a 1:1 ratio with thrombin, measuring it provides a reliable snapshot of how much thrombin your body is producing. It is considered one of the best markers of in vivo thrombin generation.

F1+2 has a half-life of about 90 minutes and is cleared by the liver. Its relatively long persistence in the blood makes it more dependable than shorter-lived markers such as fibrinopeptide A for assessing ongoing coagulation activity.

F1+2 is released from the N-terminus of prothrombin wherever the prothrombinase complex (Factor Xa, Factor Va, calcium, and a phospholipid surface) cleaves prothrombin to form thrombin. Prothrombin itself is a vitamin K-dependent protein synthesized in the liver.