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Protein C Functional or Antigen, Protein S Functional or Antigen (Free or Total)

Protein C Functional/Ag, Protein S Functional/Free Ag

Proteins C and S are coagulation inhibitors produced in the liver. Vitamin K is essential for their synthesis. These proteins help stop clot formation. If the level or activity of one or both proteins is abnormally low, it may result in abnormal clot formation (thrombosis) particularly in the veins (phlebitis, miscarriages, disseminated intravascular coagulation, etc.). Protein C and S tests are often requested at the same time as other tests prescribed in thrombotic conditions (lupus anticoagulants, cardiolipin antibodies, beta-2 glycoprotein antibodies, etc.).

High levels or activities of protein C or S generally have no clinical significance. Normal levels indicate that coagulation control is likely normal. Low levels or activities that are consistent with abnormal clot formation can come from hereditary causes (mutations) or can be related to liver disorder (liver failure), vitamin K deficiency (dietary or anticoagulant such as warfarin) or related to protein C or S overuse (disseminated intravascular coagulation). Results may be falsely lowered if the sample is taken less than 10 days after a thrombotic episode and after stopping warfarin/Coumadin® for at least 2 weeks.

Term of the Week

Creatine Kinase MM (CK-MM)

CK (creatine kinase) is an enzyme (protein) found in several tissues, including muscles and the heart. Depending on the tissue, different forms of CK are present: CK-MM is primarily present in skeletal muscles, CK-MB represents 30% of CK from the heart, while CK-BB comes from the brain and smooth muscle, such as the intestinal walls. Atypical forms of CK (macro CK1 and macro CK2) can also be present. CK electrophoresis is most useful when muscular or cardiac disease does not seem to be responsible for the increased level of total CK.