PROTEIN C ACTIVITY IS A BLOOD TEST THAT MEASURES THE FUNCTIONALITY OF PROTEIN C, A NATURAL ANTICOAGULANT IN THE BODY THAT HELPS PREVENT EXCESSIVE BLOOD CLOTTING. LOW PROTEIN C ACTIVITY INCREASES THE RISK OF DEVELOPING BLOOD CLOTS, SUCH AS DEEP VEIN THROMBOSIS (DVT) AND PULMONARY EMBOLISM. THIS TEST IS OFTEN ORDERED WHEN THERE IS A SUSPICION OF AN INCREASED CLOTTING RISK DUE TO FAMILY HISTORY, PREVIOUS BLOOD CLOTS, OR OTHER RISK FACTORS.

THIS ASSAY IS USED AS AN ADJUNCT TO INITIAL TESTING BASED ON THE RESULTS OF PROTEIN S ANTIGEN ASSAY. IT HELPS IN EVALUATING PATIENTS WITH HISTORY OF VENOUS THROMBOEMBOLISM AND DIAGNOSING CONGENITAL / ACQUIRED PROTEIN S DEFICIENCY. ONLY FREE PROTEIN S HAS ANTICOAGULANT ACTIVITY.

THIS ASSAY IS USED FOR EVALUATION OF PATIENTS WITH INCIDENT OR RECURRENT VENOUS THROMBOEMBOLISM, WITH FAMILY HISTORY OF VENOUS THROMBOEMBOLISM AND IN WOMEN WITH RECURRENT MISCARRIAGE OR COMPLICATIONS OF PREGNANCY. IT MAY ALSO BE USED FOR EVALUATING INDIVIDUALS WITH HISTORY OF ARTERIAL THROMBOSIS.

THIS TEST MEASURES THE FUNCTIONAL ACTIVITY OF ANTITHROMBIN, A PROTEIN THAT HELPS PREVENT BLOOD CLOTS. LOW ANTITHROMBIN ACTIVITY CAN INDICATE AN INCREASED RISK FOR THROMBOSIS (BLOOD CLOTS), SUCH AS DEEP VEIN THROMBOSIS (DVT) OR PULMONARY EMBOLISM (PE). IT CAN BE CAUSED BY A GENETIC DEFICIENCY, LIVER DISEASE, OR OTHER CONDITIONS.