Clinical management of protein C deficiency.

Protein C (PC) is a vitamin K-dependent plasma protein that is structurally similar to other coagulation factors such as prothrombin and Factor X. PC is converted to its active anticoagulant form by a thrombin-thrombomodulin complex on the surface of capillary endothelial cells. Activated PC (APC) prevents the formation of blood clots by specifically inactivating factors Va and VIIIa in the clotting cascade. Both acquired and hereditary forms of PC deficiency exist, with hereditary further categorised as heterozygous, homozygous as well as doubly heterozygous. Patients suffering from symptomatic heterozygous PC deficiency present with purpura fulminans, venous thrombosis and/or pulmonary embolism. Homozygous PC deficiency is usually associated with the development of severe and often fatal, purpura fulminans and disseminated intravascular coagulation (DIC) during the neonatal period. Various therapeutic options have been described for long-term management of severe heterozygous and homozygous PC deficiencies. For the treatment of heterozygous PC deficiency, oral anticoagulation with a coumarin derivative or heparin therapy remains standard therapy. Homozygous patients may be treated with fresh frozen plasma (FFP) and iv. PC concentrate or coumarin derivatives. Other therapeutic options for the treatment of hereditary PC deficiency include the use of low-molecular weight heparin (LMWH), steroids and liver transplantation. Maintenance of a symptom-free life depends on response to therapy. Patients responding well to treatment can expect normalisation of haemostasis as well as improvement of microcirculation and resolution of purpura fulminans.