Related Experiment Video
Updated: Oct 3, 2026

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Warfarin-induced skin necrosis associated with Factor V Leiden and protein S deficiency
1Department of Haematological Medicine, King's College Hospital, Denmark Hill, London, UK. tsfng@hotmail.com
Abstract:
Thrombotic events are rare complications during anticoagulation therapy. The thrombosis varies from localized cutaneous involvement to catastrophic thromboembolism and is usually associated with an underlying thrombophilia. We describe a patient who developed skin necrosis during warfarin treatment for a pulmonary thromboembolism. The management was complicated by the development of heparin-induced thrombocytopenia and further thrombotic events. Thrombophilia screen demonstrated the presence of protein S deficiency and Factor V Leiden as the prothrombotic factors, together with the demonstration of antiplatelet factor 4 antibodies, which confirms the diagnosis of heparin-induced thrombocytopenia (type II). Reinstitution of warfarin at a low loading dose was successful without the recurrence of skin lesions nor any further thrombosis.
Related Concept Videos
Anticoagulant Drugs: Low-Molecular-Weight Heparins
Anticoagulant Drugs: Vitamin K Antagonists and Direct Oral Anticoagulants
Warfarin, a prominent vitamin K antagonist family member, exerts its effect by inhibiting the enzyme VKORC1 (vitamin K epoxide reductase complex 1). By hindering this enzyme, warfarin...
Venous Thrombosis III: Interprofessional Care
Venous Thrombosis IV: Nursing Management
Disorders of Hemostasis
Thromboembolic Disorders
Two factors primarily cause thromboembolic conditions.
Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
