Von Willebrand factor degrading protease - ADAMTS-13

General Information

Von Willebrand factor is a component of the blood coagulation system that initiates blood coagulation, namely platelet adhesion.

Von Willebrand's disintegrating protease ADAMTS-13 (eng. a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) is a metalloprotease that limits the formation of microthrombi and platelet aggregates in the blood stream by cleaving the Willebrand factor.

Deficiency of the mentioned protease (enzyme) develops with the deficiency of its coding gene -ADAMTS-13, or with the development of autoantibodies against protease molecules. caused by

The test looks for ADAMTS-13 protease (enzyme) activity – its ability to break down Willebrand factor, or the presence of antibodies to the protease. If ADAMTS-13 protease activity is decreased (due to ADAMTS-13 gene mutation or development of antibodies against protease), there is an accumulation of large Willebrand factor molecules in the blood, which causes aggregation (sticking) of platelets in small-caliber blood vessels and the formation of thrombotic thrombocytopenic purpura. This study is used to diagnose thrombotic thrombocytopenic purpura and differentiate it from other diseases.

When is the survey conducted?

• When the diagnostics of idiopathic or genetic thrombotic thrombocytopenic purpura is suspected (with a negative Coombs test)
• To determine the severity of the course of thrombotic thrombocytopenic purpura and to evaluate the effectiveness of treatment
• To assess the risk of recurrence in patients in remission
• For differential diagnostics with other diseases caused by microangiopathy (liver failure, connective tissue diseases, hemolytic-uremic syndrome, post-transplantation conditions, neoplasms, HIV infection, pregnancy complications, etc.)

Preparation of the patient: It is better to conduct the research before the exacerbation of the disease, in the phase of remission.

Study sample: Venous blood.

Reference boundaries

Antibodies: <12 units/ml

Activity: 0.40 – 1.30 IU/ml

Antigen 0.41 - 1.41 IU/ml

Interpretation of results

Assessment of ADAMTS-13 activity provides the diagnostics of thrombotic thrombocytopenic purpura in the acute phase of the disease, while determination of the protease antigen provides information on the disease status of the disease.

idiopathic Thrombotic thrombocytopenic purpura in the acute phase

• A sharp decrease in ADAMTS-13 protease activity, together with a high antibody titer, most likely indicates the acute phase of the disease.
• An increase in the titer of antibodies is a poor prognostic indicator of the disease
• The level of ADAMTS13 antigen may change dramatically, without corresponding to the clinical picture of the disease.
• Severe ADAMTS13 protease deficiency is often associated with mortality.

idiopathic Thrombotic thrombocytopenic purpura in the remission phase

During disease remission, antigen levels return to normal much faster than activity.

Persistent or recurrent ADAMTS-13 protease deficiency during remission indicates an increased risk of disease exacerbation.

A false normal value of ADAMTS-13 protease activity can be observed if the study is performed immediately after plasmapheresis or blood transfusion.