Thrombogenesis and Thrombotic Disorders

Abstract

Patients who have spontaneous venous or arterial thrombosis are said to be in a “hypercoagulable state” or have “thrombophilia.” These terms are not clearly defined; however, persons in whom blood clots develop, either spontaneously or in high-risk situations (Table 1), likely have an underlying thrombophilia or hypercoagulable state, unlike persons who do not have development of blood clots in similar high-risk situations. Unlike the bleeding disorders, in which a global laboratory test (bleeding time, prothrombin time, or activated partial thromboplastin time) can predict a propensity to bleed, no global test can predict a propensity for development of inappropriate thrombosis. Thus, the usual approach to the patient with thrombosis consists of establishing the presence or absence of known risk factors for thrombosis (Table 1), obtaining a thorough personal and family history, and performing a physical examination. Subsequently, specific laboratory tests for inherited and acquired conditions that predispose to thrombosis may define the cause of the thrombus and aid in estimating the risk for recurrence. This information will influence the duration of anticoagulant therapy.