The determination of the co-factor aristocetin is used for the laboratory control and differential diagnosis of von Willebrand disease and for the treatment of the disease.
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Von Willebrand disease is an autosomal recessive disorder inherited from the predominant type and due to a defect in coagulation factor VIII. This is a blood clotting disorder that results in varying degrees of bleeding abnormalities. Coagulation factor VIII has three properties, pre-coagulation activity (the von Willebrand circulating factor has recently been identified as a factor that may initiate platelet adhesion), antigenic activity and von Willebrand factor activity. The activity of von Willebrand factor VIII enhances platelet thrombus formation.
In this test, von Willebrand factor VIII activity is measured using a modified platelet aggregation test. In normal patients or patients with haemophilia A, the antibiotic aristocetin induces platelet aggregation. In patients with von Willebrand's disease, addition of ristosetine to the patient's serum does not cause platelet aggregation. The lower the platelet aggregation rate, the lower the amount of von Willebrand factor.
The test helps differentiate between haemophilia A (classical haemophilia) and von Willebrand's disease.
Von Willebrand factor values may increase by 2-3 times during pregnancy. Increased values may also occur during stress, infection, inflammatory conditions, postoperatively, or after intense physical activity. Patients with blood group C may have up to 30% lower von Willebrand factor values than patients with other blood groups.
The measurement of the ristocetin cofactor is done in combination with the measurement of the von Willebrand factor antigen.
Important Note
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.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
