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Prothrombin Fragment 1+2

Meaning

Prothrombin Fragment 1+2 (F1+2) is a specific peptide released into the circulation during the conversion of the coagulation protein prothrombin to thrombin, a key enzyme in the blood clotting cascade. As a stable, non-functional byproduct, its concentration in the plasma serves as a reliable, quantitative biomarker of ongoing in vivo thrombin generation and overall coagulation system activation. Clinically, elevated F1+2 levels indicate a hypercoagulable state, which is particularly relevant in assessing the thrombotic risk associated with certain hormonal therapies, such as oral estrogens.