Venous Thromboembolic Disease: Risk Factors and Laboratory Investigation

Abstract

The etiology of venous thromboembolic disease has been the subject of several recent discoveries, particularly on genetic predisposing factors. The laboratory investigation that may help to evaluate the risk for individual patients includes the measurements of coagulation inhibitors (antithrombin, protein C, and protein S) in plasma assays, the search for the factor V Leiden mutation by the plasma activated protein C resistance test (always to be confirmed by DNA analysis when abnormal), and the search for the prothrombin gene mutation by DNA analysis. Among acquired abnormalities, the most frequently involved are phospholipid-dependent autoantibodies associated or not with a subset of antibodies having an anticoagulant effect in vitro (lupus anticoagulant). Other coagulation abnormalities such as increased FVIII, FIX, or FXI levels or hyperhomocysteinemia have been suggested to be risk factors for thrombosis, although additional studies are required to definitively assess their role.

Inhibition of Platelet Glycoprotein Ib and Its Antithrombotic Potential

“…However, the correlation between FXI plasma levels and bleeding tendency is low. On the other hand, it is suggested that an increased FXI level is a risk factor for thrombosis [121]. Thrombus formation upon ferric chloride induced injury of the carotid artery was defective in FXI-deficient mice [122] and could be restored by injection of exogenous FXI.…”

Assessment of risk of venous thromboembolism and its possible prevention in psychiatric patients

“…We preferred an exponential allocation of a risk magnitude to an even one because the risk of VTE significantly increases if several causative factors are present at the same time. In this case, the individual odds ratios are not simply added but are multiplied by each other 1,2 . We recommend adequate clinical prevention steps pursuant to every risk range.…”

“…In contrast, mutation in factor V Leiden or prothrombin genes, deficiency of antithrombin, protein C or S, hyperhomocysteinemia, high concentrations of factors VIII, IX or XI, antiphospholipid syndrome, disfibrinogenemia, and abnormal fibrinolysis are prominent laboratory risk factors. Combination of several factors increasing the risk of VTE in one patient at the same time is common 1,2 . Risk of VTE is increased in psychiatric patients as compared to mentally healthy people, 3,4 especially in schizophrenia and bipolar disorder 5 .…”

Antipsychotic drugs as a risk factor for venous thromboembolism

“…In this case, the individual odds ratios are not simply added, but multiplied by each other [13,14]. Even if some researchers propose the possibility that VTE may be associated with schizophrenia itself via autoimmune mechanisms [15] or increased homocysteine serum level [16] instead of the medication, we do not suppose that the mental disorder led to thrombosis.…”