Protein C Functional, Sodium Citrate Whole Blood

Protein C test along with protein S, helps to investigate for any hypercoagulable disorder in which there is excess clotting. Protein C and protein S tests also help to diagnose the cause of inappropriate thrombus (blood clot) formation such as deep venous thrombosis (DVT) or a venous thromboembolism. Protein C and protein S are vitamin K-dependent anticoagulants synthesized by the liver. Protein C circulates in the blood (plasma) and protein S is present in the platelets. The half-life of protein C is 6 to 10 hours. Thrombin in the presence of thrombomodulin (endothelial cell cofactor) activates protein C and protein S. These activated forms act as anticoagulant by inactivating the active forms of coagulation factors like factor V and factor VIII. Protein C also enhances fibrinolysis by inactivating plasminogen activator inhibitor (PAI-1). The activity of activated protein C is enhanced by protein S. Protein S also has a direct Activated Protein C independent anticoagulant activity. Deficiency of protein C and protein S results in thrombotic events (mostly venous thromboemboli; arterial thrombosis results in stroke, myocardial infarction etc). However at times it could be asymptomatic. Hereditary heterozygous protein C deficiency is of two types: Type I, associated with decreased protein C antigen and activity and type II which is associated with decreased protein C function and normal antigen levels. There are 3 types of protein S deficiencies, according to the levels of total and free protein S antigen and protein S activity. Types I and III protein S deficiency are more common than type II protein S deficiency. Vitamin K deficiency, oral anticoagulants, liver diseases etc are associated with acquired form of protein C and protein S deficiencies. Protein C functional activity assay is advised when suspecting congenital protein C deficiency. Based on the results of protein C activity - protein C antigen, protein S tests may be needed, to classify and determine the severity of disorder. It is advised to look for acquired causes of protein C deficiency, such as Vitamin K deficiency, oral anticoagulants, liver diseases etc.