Found in 0.2% of the general population.
Protein C deficiency is inherited in an autosomal dominant pattern.
Two classifications: type I and type II.
Type I deficiency results from an inadequate amount of protein C.
In type I deficiency there are manany protein C defects have been described that alter interactions with thrombomodulin, phospholipids, factor Va and factor VIIIa.
Protein C in plasma in the steady state has a half life of 6- to 10-hours.
Estimated incidence annually of deep vein thrombosis is 1 episode for every 1000 persons.
Patients born with both of the copies of the abnormal protein C gene, homozygous deficiency, often have purpura fulminans, a severe form of thrombosis, with severe clotting throughout the body and can lead to death of tissues, a life threatening condition.
Treatment in the presence of a venous clot requires anticoagulation for 3-6 months.
Recurrent episodes of thromboembolic episodes may require long-term anticoagulation.
In patients with homozygous disease risk of death from thrombosis is imminent and use of FFP or protein C concentrates are needed.
Patients with severe protein C deficiency and presenting with purpura fulminans can be treated acutely with an initial bolus of protein C concentrate 100 IU/kg followed by 50 IU /kg every 6 hours.
A total of 1 IU/kg of protein C concentrate or 1 mL/kg of fresh frozen plasma will increase the plasma concentration of protein C by 1 IU/dL.
Cases with comorbid pathological bleeding may require additional transfusions with platelet concentrate or cryoprecipitate (5 mL/kg).