Laboratory investigation of thrombophilia: the good, the bad, and the ugly.
Thrombophilia can be broadly defined as an increased tendency toward hypercoagulability and venous thrombosis. There are several defined risk factors for thrombosis, and these are generally distinguished as either acquired or congenital, although sometimes this distinction is blurred because of interrelationships. Congenital risk factors include deficiencies or defects in natural anticoagulants, such as antithrombin, Protein C and Protein S, and genetic polymorphisms such as prothrombin G20210A and cleavage-resistant forms of factor V (in particular factor V Leiden), that lead to a condition commonly known as activated protein C resistance. Acquired risk factors include antiphospholipid antibodies, detected as lupus anticoagulants and/or anticardiolipin antibodies and/or anti-beta-2-glycoprotein-I antibodies. High levels of clotting factors, dysfibrinogenemia, hyperhomocysteinemia, prolonged immobilization, increasing age, surgery, trauma, cancer, obesity, poor nutrition, pregnancy, oral contraceptives, and hormone replacement therapy comprise just some of the other risk factors. Each of these elements constitutes a component of increased risk, which is compounded when concomitant. There is ongoing debate regarding relative and compound risks, the value of laboratory screening, whom and when to screen for these markers, which tests and methodologies to use, and the form and duration of therapeutic management. The current article explores several important issues primarily from a scientific perspective and predominantly related to laboratory testing. Many of these issues appear to be simply overlooked by some clinicians managing patients with thromboses. In brief, although there is potential significance in testing for various thrombophilia-associated markers, this value is limited and greatly diminishes when inappropriately applied. The application of excessive or inappropriate thrombophilia testing is of particular concern, and the net effect of current worldwide testing trends is likely to be more detrimental than beneficial. In short, it is likely that current generalized testing is simply doing more harm than good, and thus that ordering practice requires scrutiny.
Favaloro
Emmanuel J
EJ
Department of Haematology, Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, NSW, Australia. emmanuel.favaloro@swahs.health.nsw.gov.au
McDonald
David
D
Lippi
Giuseppe
G
D000925:Anticoagulants / Q000009:adverse effects; D003951:Diagnostic Errors; D006403:Hematologic Tests; D006801:Humans; D012307:Risk Factors; D019851:Thrombophilia / Q000097:blood* / Q000150:complications / Q000175:diagnosis* / Q000235:genetics; D013927:Thrombosis / Q000097:blood / Q000150:complications*
D000925:Anticoagulants