Measurement of plasma S protein activity is used to investigate patients with congenital or acquired S protein deficiency as well as in patients with a family history of depression or in patients who have already experienced a thromboembolic event.
Protein S is found in plasma, is a glycoprotein dependent on vitamin K, synthesized in the liver and involved in the blood coagulation process. Protein S is present in the free form which is the active form and bound to the 4Cb (4Cb-BP) binding protein, which is an inactive form. Protein S acts as a cofactor in protein C, which inactivates the coagulation factors Va and Vllla.
S protein deficiency can be of two types. Congenital deficiency of protein S, which is a predominant type of autosomal disorder responsible for approximately 5% of thrombosis and in which the patient has a higher than normal risk of thrombosis at an early age. Acquired deficiencies of S protein are apparent in pregnancy, diffuse intravascular coagulation, liver disease and in patients receiving warfarin. Deficiency of protein S is mainly responsible for the occurrence of venous thrombosis and less arterial thrombosis.
Three types of hereditary heterozygous S protein deficiency have been described according to levels of total protein S, free protein S, and protein S activity. Type I and III deficiencies of protein S are much more common than type II deficiency.
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.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of 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 interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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