protein S deficiency

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Protein S deficiency results in a primary hypercoagulable state.

Both quantitative and qualitative abnormalities of protein S have been identified.

In the normal individual, 60% of protein S in the plasma is inactive, being bound to the C4b-binding protein. Excessive binding of protein S to C4b-binding protein may result in a deficiency of active protein S in the plasma.

Protein S deficiency is associated with (1):

  • 10x increased risk of thrombosis
  • 3% prevalence in patients with venous thromboembolism
  • 2% prevalence in normal population


(1) British Heart Foundation (Factfile 2/2002). Thrombophilia.

Last reviewed 01/2018