Protein S

Reference values ​​of the concentration of total protein S in blood plasma - 60-140%, free - 65-144%.

Protein S is a vitamin K-dependent plasma glycoprotein. It circulates in the blood in two forms: free( 40%) and associated with the C4-component

complement( 60%).They are in dynamic equilibrium, but only free protein is active. Protein S is a cofactor of protein C in the process of inactivation of Va and VIIIa of clotting factors [Barkagan ZS, 1988].The currently available ELISA test systems allow the determination of the concentration of free protein S, which is of paramount importance for clinical practice.

The content of protein S in the blood of men is higher than that of women. Indirect anticoagulants affect it weaker than on protein C, this is due to the fact that protein S is synthesized in endothelial cells of the liver and megakaryocytes. With liver diseases, its level is higher than that of protein C. Since the bulk of protein S is associated with the C4 complement component, the amount of free protein S decreases with increasing C4 concentration( acute phase of inflammatory diseases or exacerbation of chronic).Reducing the concentration of protein S in the blood is possible with nephrotic syndrome due to its loss.

Classification of protein deficiency S

■ Type I - deficiency of total protein S.

■ Type II - deficiency of free protein S at normal or borderline content of total protein S.

■ Type III - protein S dysfunction with reduced anticoagulant activity.

Deficiency of protein S leads to the development of venous thrombosis, especially in young people.

In Table.data on the effect of changes in anticoagulant system indices on the risk of thrombohemorrhagic complications are presented.

Table Anticoagulant system parameters and risk factors for thrombohemorrhagic complications

Table Anticoagulant system parameters and risk factors for thrombohemorrhagic complications

Table.the main effects of endogenous and exogenous anticoagulants are presented.

Table The main points of application of the action of anticoagulants