Protein S Activity details
What Protein S Activity shows
Protein S is a natural anticoagulant protein that works together with Protein C to help regulate and limit blood clot formation, keeping your clotting system in balance. This test measures Protein S activity, and low activity — from an inherited deficiency or acquired causes like pregnancy, liver disease, vitamin K deficiency, or certain medications — raises the risk of developing abnormal blood clots. It's typically ordered as part of a broader clotting disorder workup after an unexplained blood clot, often alongside Protein C and antithrombin testing.
Tests that include Protein S Activity
This profile helps to confirm and characterize congenital deficiency of protein S.
- Protein S Activity Measures the activity of Protein S, a natural anticoagulant that works with Protein C. Low activity raises the risk of blood clots.
- Protein S Antigen, Free The unbound, biologically active portion of Protein S, a natural anticoagulant. Low levels raise the risk of blood clots.
- Protein S Antigen, Total Measures the total amount of Protein S — both free and bound forms — a natural anticoagulant. Low levels raise the risk of blood clots.
This profile helps to confirm and characterize congenital deficiency of protein S.
- Protein S Activity Measures the activity of Protein S, a natural anticoagulant that works with Protein C. Low activity raises the risk of blood clots.
- Protein S Antigen, Free The unbound, biologically active portion of Protein S, a natural anticoagulant. Low levels raise the risk of blood clots.
- Protein S Antigen, Total Measures the total amount of Protein S — both free and bound forms — a natural anticoagulant. Low levels raise the risk of blood clots.
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