VA-test

List of reagents with composition

Set of reagents for determination of lupus anticoagulant (LA test) according to TU 9398-018-05595541-2008 is intended for coagulological determination of the presence of LA in the blood plasma of patients according to the criteria of the Subcommittee on Science and Standardization of the International Society on Thrombosis and Hemostasis.

In the pathogenesis of antiphospholipid syndrome, the presence of lupus anticoagulant (LA), a group of similar inhibitors of blood coagulation belonging to immunoglobulins of class IgG and IgM, plays a leading role. Their presence leads to the development of both arterial and venous thrombosis against the background of various diseases: systemic lupus erythematosus, rheumatoid arthritis, etc. In addition, lupus anticoagulant is associated with various pregnancy pathologies, such as miscarriage, fetal growth restriction syndrome, stillbirth.

Method Principle: The method for determining LA is based on its property to inhibit phospholipids, thereby prolonging the clotting time in APTT tests, diluted Russell's viper venom time, prothrombin time, kaolin time, etc. The Subcommittee on Science and Standardization of the International Society on Thrombosis and Hemostasis has proposed the following criteria for the diagnosis of LA:

• Prolongation of one or more phospholipid-dependent tests,
• Lack of correction of the test extension by adding an equal volume of normal plasma, and
• Absence of specific inhibitors of any factors in the blood clotting system.

At the first stage, tests are conducted to detect LA, using reagents with a low phospholipid content to enhance the difference between normal and pathological plasmas (screening tests). If the clotting time is prolonged, it is determined whether this is associated with dysfunction of coagulation factors or the presence of inhibitors. For this purpose, tests are performed by adding to the incubation medium normal plasma containing all coagulation factors. Prolongation of the clotting time of the mixture of normal and test plasma indicates the presence of coagulation inhibitors.

To establish the nature of the inhibitors, further tests are carried out with reagents containing a high concentration of phospholipids or platelet membranes to deplete the anticoagulant effect of LA (confirmatory tests). Shortening of the clotting time in this case will indicate the presence of LA in the test plasma.