Protein C Activity details
What Protein C Activity shows
Protein C is a natural anticoagulant protein made by the liver that helps put the brakes on excessive blood clotting, working together with Protein S to inactivate certain clotting factors once a clot has done its job. This test measures how well Protein C is functioning, and low activity — whether from an inherited deficiency or acquired causes like liver disease, vitamin K deficiency, or active blood clot formation itself — is linked to an increased risk of developing abnormal blood clots. It's typically ordered as part of a broader clotting disorder workup after an unexplained blood clot, especially in younger people or those with a family history.
Tests that include Protein C Activity
Aids in characterization of protein C deficiency. Type I deficiency is characterized by reduction in activity (functional) and antigen levels. With type II deficiency (dysfunctional protein), antigen levels may be normal and activity levels are decreased. Acquired deficiencies may occur with vitamin K antagonists/deficiency, liver disease, malignancy, consumptive DIC, surgery, trauma, and hepatic immaturity of the newborn. Drug therapy with L-asparaginase or fluorouracil can also reduce Protein C antigen levels.
- Protein C Activity Measures the activity of Protein C, a natural anticoagulant. Low activity is linked to an increased risk of blood clots.
- Protein C Antigen Measures the actual amount of Protein C protein present, used together with the activity test to fully characterize a Protein C deficiency.
The Thrombotic Risk Assessment assesses an individual's risk for developing a thrombotic event, such as a stroke or heart attack, by measuring factors affecting blood clotting.
- Homocysteine An amino acid byproduct of protein metabolism. Elevated levels are linked to increased cardiovascular risk and can reflect low B vitamin (B12, folate, B6) status.
- Protein C Activity Measures the activity of Protein C, a natural anticoagulant. Low activity is linked to an increased risk of blood clots.
- Activated Protein C Resistance Checks whether your blood resists the natural anticlotting action of activated protein C, most often caused by the inherited factor V Leiden variant.
- Antithrombin III Activity Measures the activity of a protein that naturally helps prevent excessive blood clotting. Low levels are linked to an increased risk of blood clots.
- Beta-2-Glycoprotein I Antibody (IgA) Measures IgA antibodies against beta-2-glycoprotein I, one of the antiphospholipid antibodies, used to evaluate antiphospholipid syndrome and causes of blood clots.
- Beta-2-Glycoprotein I Antibody (IgG) Measures IgG antibodies against beta-2-glycoprotein I, one of the antiphospholipid antibodies, used to evaluate antiphospholipid syndrome and causes of blood clots.
- Beta-2-Glycoprotein I Antibody (IgM) Measures IgM antibodies against beta-2-glycoprotein I, one of the antiphospholipid antibodies, used to evaluate antiphospholipid syndrome and causes of blood clots.
- Cardiolipin Antibody (IgA) An antibody that attacks the body's own phospholipids (IgA type). One of the markers used to help diagnose antiphospholipid syndrome, which raises the risk of blood clots and pregnancy complications.
- Cardiolipin Antibody (IgG) An antibody that attacks the body's own phospholipids (IgG type). One of the markers used to help diagnose antiphospholipid syndrome, which raises the risk of blood clots and pregnancy complications.
- Cardiolipin Antibody (IgM) An antibody that attacks the body's own phospholipids (IgM type). One of the markers used to help diagnose antiphospholipid syndrome, which raises the risk of blood clots and pregnancy complications.
- Dilute Russell's Viper Venom Time (DRVVT) Screen A clotting test that helps screen for lupus anticoagulant, an antibody linked with a higher risk of blood clots and some pregnancy complications.
- Factor II (F2) DNA Analysis A genetic test for the prothrombin (Factor II) G20210A variant, an inherited change in the F2 gene that can raise the tendency to form blood clots.
- Lupus Anticoagulant Detects lupus anticoagulant, an antiphospholipid antibody that prolongs clotting tests in the lab but is linked to an increased risk of blood clots.
- Plasminogen Measures the activity of plasminogen, the protein that becomes plasmin to break down blood clots, used when assessing clotting and bleeding risk.
- Protein S Antigen, Free The unbound, biologically active portion of Protein S, a natural anticoagulant. Low levels raise the risk of blood clots.
- PTT-LA Screen A clotting-time screen sensitive to lupus anticoagulant, an antibody linked to blood clots, used as a first step in antiphospholipid testing.
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