Protrombinowy

Protrombinowy refers to prothrombin, a vitamin K–dependent glycoprotein produced in the liver that acts as a zymogen in the coagulation system. Prothrombin is the precursor of thrombin, the enzyme that converts fibrinogen to fibrin and activates various coagulation factors. The synthesis of functional prothrombin depends on gamma-carboxylation of glutamic acid residues, a reaction that requires vitamin K.

In the coagulation cascade, prothrombin is activated by the prothrombinase complex (comprising factor Xa, factor Va, calcium ions and phospholipids) to form thrombin. Thrombin then amplifies clot formation by converting fibrinogen into fibrin, activating platelets, and promoting further activation of coagulation factors. Anticoagulants such as warfarin reduce the production of functional prothrombin, thereby prolonging coagulation time.

Czas protrombinowy, or prothrombin time (PT), is a laboratory test that measures how long plasma takes to clot after the addition of tissue factor (thromboplastin) and calcium. PT primarily assesses the extrinsic and common pathways of coagulation and is influenced by factors VII, II, V and X. It is commonly used to monitor oral anticoagulant therapy (for example, warfarin) and to evaluate liver function and vitamin K status. Results are often reported as the International Normalized Ratio (INR), which standardizes PT across laboratories.

Clinically, abnormal protrombinowy results can indicate vitamin K deficiency, liver disease, antibiotic-induced disruption of gut microbiota, malabsorption, or anticoagulant therapy. Deficiency or dysfunction of prothrombin (factor II) itself can cause bleeding diatheses, underscoring its essential role in hemostasis.