Measurement of protein S activity in plasma is used to screen patients for congenital or acquired protein S deficiency, as well as in patients with a strong family history or in patients who have already experienced a thromboembolic event.
More information
Protein S is a vitamin K-dependent glycoprotein found in plasma, synthesized in the liver, and involved in the blood coagulation process. Protein S exists in a free form, which is the active form, and bound to 4Cb-binding protein (4Cb-BP), which is the inactive form. Protein S is a cofactor for protein C, which inactivates coagulation factors Va and VIIIa.
There are two types of Protein S deficiency. Congenital protein S deficiency is an autosomal dominant disorder responsible for approximately 5% of thrombosis, and the patient is at a higher risk of thrombosis at a young age. Acquired protein S deficiencies become evident in pregnancy, disseminated intravascular coagulation, liver disease, and patients taking warfarin. Protein S deficiency is mainly responsible for venous thrombosis and, less often, arterial thrombosis.
Three types of inherited heterozygous protein S deficiency have been described according to the levels of total protein S, free protein S, and protein S activity. Type I and III protein S deficiencies are much more common than type II (dysfunction).
Possible Interpretations of Pathological Values
- Increase: -
- Decrease: Acute consumption (as in diffuse intravascular coagulation), congenital S protein deficiency, pregnancy, kidney disease, vitamin K deficiency. Medications: Aparaginase, oral contraceptives, 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.
