Table 1.

Possible etiology for thrombosis

Description	Cause
I. Injury of vascular endothelial cells	Mechanical (atherosclerosis), chemical (medication), or biologic (endotoxin)
II. Increase in platelet amount and activity	Thrombocytosis, injuries caused by mechanical, chemical, or immune factors
III. Increased blood coagulation	Pregnancy, advanced age, trauma, or tumor
IV. Decreased anticoagulant activity	Decreased antithrombin, protein C, S, or vitamin B12 deficiency, hyperhomocysteinemia
V. Decrease of fibrinolytic activities	Abnormality of plasminogen activator release or increased inhibition
VI. Abnormality of hemorheology	Hyperfibrinogenemia, hyperlipidemia, dehydration, or polycythemia