Plasma C protein activity is used to investigate patients with congenital or acquired C protein deficiency, patients with a severe family history, and patients who have already experienced a thromboembolic episode.
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Activated protein C is found in plasma, is a glycoprotein dependent on vitamin K, and acts as an anticoagulant by inhibiting coagulation factors V and XIII. Protein C was first identified in the early 1980s. 60% of protein C is bound to a complement protein and is converted to its activated functional form by the action of a protease. A cofactor, S protein, enhances its activity.
Protein C deficiency can be congenital or acquired.
Congenital protein C deficiency is an inherited, dominant type of autosomal thrombophilia responsible for 3-5% of venous thrombosis cases. It can manifest either as reduced levels of protein C or as resistance to protein C despite its normal levels. Patients with homozygous deficiencies usually die of thrombosis during their first year of life. Patients with heterozygous protein C deficiency often have thromboembolic episodes of venous thrombosis, such as deep vein thrombosis or pulmonary embolism, at an early age.
Acquired protein C deficiency is observed in acute respiratory distress syndrome, diffuse intravascular coagulation, hemolytic uremic syndrome, liver disease, infection, postoperative conditions, and vitamin K deficiency. Protein deficiency is responsible for much more venous than arterial thrombosis. The factor V Leiden mutation is a molecular defect in factor V that makes it resistant to anticoagulant activation by protein C. This mutation is an essential cause of deep vein thrombosis, occurring in 5% of the population.
Possible Interpretations of Pathological Values
- Increase: Diabetes, nephrotic syndrome
- Decrease: Acute consumption (as in diffuse intravascular coagulation), congenital protein C deficiency, liver disease, vitamin K deficiency. Medications: Antibiotics, asparaginase, estrogen, warfarin
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
