Protein C Deficiency

Congenital deficiency. Homozygote is estimated at 1:500,000-750,000 live births. Occurs when gene coding for protein C on both chromosomes #2 is affected.

Heterozygote ∼0.2–0.4% of healthy population; 2–5% in pts with DVT.

Acquired deficiency also seen.

Pts with protein C deficiency are at risk for venous thrombosis and pulm embolism (immobility, endothelial damage, and decreased blood flow during periop period may be triggers).

Increased incidence of thrombophlebitis and pulm embolism

Thrombosis of other vessels, such as intracerebral and coronary arteries, can occur.

Protein C is a vitamin K–dependent protein found in blood and synthesized in the liver.

Activated after forming a complex with thrombin on endothelial cell receptor thrombomodulin; facilitated by binding to endothelial cell protein C receptors.

Inhibits blood coagulation by proteolytic inactivation of factors V and VIII.

Protein S is a cofactor of protein C.

Stimulates fibrinolysis possibly by neutralizing plasminogen activator inhibitors

Deficiency causes hyperthrombotic state

During SIRS and sepsis, there is decreased synthesis of protein C.