2. หลังยังพบว่า factor อื่นที่ทำให้เกิด venous thrombosis คือ –prior thrombosis5+ –non - type O blood 4+ – อายุมากกว่า > 35 ปี 3+ –BMI1+ จาก risk factor scoring for predicting venous thromboembolism ของ Peter S. Bern stein, MD, MPH in the american college of obstertricians and Gynecologists 48 th Annual Clinical Meeting
Naturally occuring anticogulants 1.Antithrombin III (ATIII) The most important inhibitor of coagulation factors –the presence of heparin –heparin’s effeect on ATIII is enhancement of preexisting activity Sites of action –inhibit many serine protease enzymes ( Thrombin & factors Xa IXa and Xia )
Protein C The inactive precursor form of the anticoagulant ( Protein Ca) which is a serine protease that acts on specific clotting factors in the cofactors Protein S Both protein C and protein S are vitamin K- dependent Requires thrombin and thrombomodulin Sites of action –coagulation –fibrinolysis
Fibrinolysis The body’s system for dissolution of clots has similarities to the coagulation mechanism Sites of action –capable of dedegrading a variety of protein –under conditions plasmin acts primarily on fibrin –In conditions of enhanced plasmin activity fibrinogen
Thrombotic disorder Congenital thrombotic Inherited abnormalities that predispose to thrombosis must be considered in patients who experience thromboembolic disease
ATIII deficiency An autosomal dominant disorder with an estimated prevalence of 1 in 2000 individuals –Thrombosis –Heparin resistance
Protein C deficiency This autosomal dominant disorder may be the most common of the in herited thrombotic abnormalities An estimate 1 in 300 individuals are heterozygous for protein C deficiency Protien C deficiency is associated with three distinct clinical syndromes –Thromboembolic disease –Warfarin - induced necrosis –Purpura fulminans neonatalis
Protein S deficiency Similar to those of protein C deficiency and ATIII deficiency. Other –Inherited abnormalities of plasminogen, fibrinogen, and other plasma proteins have also been reported to be associated with thrombotic disorders, but they appear to be much less frequent than the disorders discussed above.