Subtherapeutic INR Levels in Patients With AVK: Incidence, Associated Factors, Prognosis and Control Strategies

The vitamin K antagonists exert their anticoagulant effect through inhibition of the enzyme complex of vitamin K epoxide reductase subunit 1 with subsequent reduction of the gamma-carboxylation of certain glutamic acid molecules endpoints located on factors coagulation II (prothrombin), VII, IX and X and protein C or its cofactor protein S. This gamma-carboxylation has a significant bearing on the interaction of coagulation factors referenced with calcium ions. Without this reaction, blood clotting cannot be initiated. The dose must be adjusted to each patient at baseline and after regular basis, since the sensitivity to anticoagulants varies between individuals and can also vary throughout the treatment. For this, the Prothrombin Time (PT) is used and standardized ratio called International Normalised Ratio (INR).