Overview: Von Willebrand Factor Ristocetin Cofactor TestIntroduction: The Von Willebrand Factor Ristocetin Cofactor Test measures vWF ristocetin cofactor to diagnose von Willebrand disease, causing bleeding. Aligned with 2023 ASH guidelines, it uses coagulation methods for high specificity, supporting coagulation screening. This test is critical for guiding diagnosis, treatment planning, and improving outcomes in coagulation for patients with suspected von Willebrand disease.
Other Names: vWF:RCo Assay, Von Willebrand Ristocetin Test.
FDA Status: Laboratory-developed test (LDT), meeting coagulation standards for diagnostic accuracy.
Historical Milestone: vWF ristocetin cofactor testing began in the 1970s with bleeding disorder research. Coagulation methods improved in the 2000s, enhancing diagnostic precision.
Purpose: Measures vWF ristocetin cofactor activity to diagnose von Willebrand disease, guides treatment, and evaluates patients with bleeding.
Test Parameters: 1. vWF Ristocetin Cofactor Activity
Pretest Condition: No fasting required. Collect citrated plasma. Report history of bleeding or coagulation disorders.
Specimen: Citrated Plasma (NaCit, 2-4 mL). Transport in a biohazard container.
Sample Stability at Room Temperature: 8 hours
Sample Stability at Refrigeration: 24 hours
Sample Stability at Frozen: Not frozen
Medical History: Document bleeding, bruising, or history of coagulation disorders. Include current medications, especially anticoagulants.
Consent: Written consent required, detailing the tests purpose, von Willebrand disease implications, and risks of sample collection.
Procedural Considerations: Uses aggregometry or ELISA to measure vWF ristocetin cofactor activity. Results are available in 1-2 days, supporting clinical decisions. Performed in laboratories, often for bleeding disorder diagnosis.
Factors Affecting Result Accuracy: Sample hemolysis or improper collection can affect results. Inflammation or stress may alter vWF activity.
Clinical Significance: Low vWF ristocetin cofactor confirms von Willebrand disease, guiding desmopressin or vWF replacement therapy. Normal levels may require other vWF tests.
Specialist Consultation: Consult a hematologist for result interpretation and treatment planning.
Additional Supporting Tests: vWF antigen, vWF collagen binding, or factor VIII to confirm von Willebrand disease diagnosis.
Test Limitations: Non-specific for disease subtype; clinical correlation is needed. Sample quality affects sensitivity.
References: ASH Hematology Guidelines, 2023; Blood, Sadler JE, 2022.
