Thomas G. DeLoughery, MD, FACP, FAWM

Oregon Health Sciences University, Portland, OR

This case was reviewed and updated in October 2012 by Dr. Alvin H. Schmaier and members of the Teaching Cases Subcommittee.

Copyright of the American Society of Hematology, 2006. ISSN: 1931-6860.


It is important to recognize that when a patient presents with an acute venous thrombosis, the tests for the diagnosis of the mechanism for the thrombus should be performed when the patient is stable on or off warfarin anticoagulants. This latter point is essential for assay of protein C or S defects/deficiencies, which are lowered by warfarin therapy. This patient had a workup during the acute event; therefore, any abnormalities detected at that time will need to be confirmed when she is clinically stable.

Which of the following laboratory examinations should be ordered?

Complete Blood Count with platelets
aPTT (activated partial thromboplastin time) and PT (prothrombin time)
Antithrombin activity and antigen
Protein C activity and antigen
Free Protein S antigen
Factor V Leiden gene polymorphism
Anticardiolipin and anti-ß2-glycoprotein 1 antibodies and lupus anticoagulant assays
Prothrombin 20210 gene polymorphism

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