Thrombophilia investigation – Not for everyone

Abstract

‘All truths are easy to understand once they are discovered; the point is to discover them’ (Galileo Galilei). Many physicians believe that a thrombophilia work-up will provide the explanation for a thrombotic event and thousands of dollars have been spent on these investigations. For arterial thromboembolic events a thrombophlia investigation is rarely positive and it will never lead to any beneficial change in management of the patients. In venous thromboembolism it can demonstrate abnormalities in up to 50% of the cases, depending on how they are selected. False positive results are common if the blood sampling is performed when an anticoagulant drug is present. The most affected tests are lupus anticoagulant, protein C, protein S and antithrombin. The acute phase reaction as well as liver dysfunction secondary to large pulmonary embolism with right heart strain can also distort the results. A negative investigation does not mean that the patient has no thrombophilic condition, since some abnormalities surely remain to be discovered. Before embarking on a thrombophilia work-up some questions need to be answered: (1) will the result change the management—probably not if the condition requires indefinite anticoagulation—and (2) if not, is it for information and preventive measures for family members, and in that case, are they interested? The evidence that such information will change prognosis is very weak. ‘All truths are easy to understand once they are discovered; the point is to discover them’ (Galileo Galilei). Many physicians believe that a thrombophilia work-up will provide the explanation for a thrombotic event and thousands of dollars have been spent on these investigations. For arterial thromboembolic events a thrombophlia investigation is rarely positive and it will never lead to any beneficial change in management of the patients. In venous thromboembolism it can demonstrate abnormalities in up to 50% of the cases, depending on how they are selected. False positive results are common if the blood sampling is performed when an anticoagulant drug is present. The most affected tests are lupus anticoagulant, protein C, protein S and antithrombin. The acute phase reaction as well as liver dysfunction secondary to large pulmonary embolism with right heart strain can also distort the results. A negative investigation does not mean that the patient has no thrombophilic condition, since some abnormalities surely remain to be discovered. Before embarking on a thrombophilia work-up some questions need to be answered: (1) will the result change the management—probably not if the condition requires indefinite anticoagulation—and (2) if not, is it for information and preventive measures for family members, and in that case, are they interested? The evidence that such information will change prognosis is very weak.