Updated: 6/24/2019

Protein C/S Deficiency

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Snapshot
  • A 40-year-old woman is bridged from heparin to warfarin for a recent provoked DVT. Soon after receiving warfarin, she develops dark lesions on her arms. They are large, dark, and necrotic. Warfarin is stopped and vitamin K and heparin are administered. Suspicious, her physician orders a specific assay that measures the activity of protein C.
Overview

Introduction
  • Hypercoagulable state/thrombophilia caused by deficiency in protein C or S
  • Genetics
    • protein C deficiency - autosomal dominant
    • protein S deficiency - autosomal dominant (much less common)
  • Pathogenesis 
    • review of anticoagulation pathway
      • protein C (with cofactor protein S) inactivates factors V and VIII
      • remember, both are vitamin K-dependent
      • both are synthesized in the liver
    • deficiency of either protein C or S → active factors V and VIII
      • thrombosis
  • Mnemonics
    • skin or subcutaneous necrosis after administration of warfarin
      • remember, warfarin affects protein C and S first
    • protein C deficiency is more common than protein S deficiency
    • “protein C Cancels Coagulation”
Presentation
  • Symptoms of thrombosis
    • after warfarin initiation 
      • skin and subcutaneous necrosis
    • DVT or PE at a young age
    • increased risk of DIC
Evaluation
  • Protein C or S functional assay (preferred)
    • ↓ protein C or S activity levels
  • Genetic testing not routinely done
Differential Diagnosis
  • Factor V Leiden mutation
  • Antithrombin deficiency
  • Antiphospholipid syndrome
  • HIT
Treatment
  • For thrombosis
    • protein C concentrate
    • anticoagulate with heparin
  • For warfarin-induced necrosis
    • stop warfarin
    • administer IV vitamin K
    • administer heparin
Prognosis, Prevention, and Complications
  • Prognosis
    • risk of thrombosis
    • risk of warfarin-induced skin necrosis
  • Prevention
    • avoid warfarin
    • avoid conditions that increase risk of thrombosis
  • Complications
    • miscarriage
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