Protein S activity, Plasma

This test is often performed to help diagnose the cause of an inappropriate blood clot such as deep venous thrombosis (DVT) or pulmonary embolism (PE) (venous thromboembolism or VTE). Congenital Protein S deficiency- is rare autosomal dominant disorder with 1 to 3% incidence of venous thromboembolism in adults. Acquired free protein S deficiencies can be found in several clinical states: Inflammatory syndrome due to the increase of C4b Bp, Hepatic Disorders, and Nephrotic syndrome treatment with oral anticoagulants. 

The test measures the levels of activated Protein C in the blood. 

The test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer. 

Low levels or deficiency of protein C suggests that your blood may clot too much. Protein S deficiency may be associated with increased risk of venous thrombosis, recurrent miscarriage, complications of pregnancy (preeclampsia, abruption placentae, intrauterine growth restriction, and stillbirth) and possibly arterial thrombosis. Patients on oral anticoagulants will have decreased protein S antigen level.
Elevated protein S levels are not usually associated with medical problems and are not clinically significant.