von Willebrand Factor Activity (Ristocetin Cofactor)
Also known as: RCF
Use
The von Willebrand Factor Activity (Ristocetin Cofactor) test is used as part of the initial diagnostic workup for suspected von Willebrand disease (VWD). It is also useful for monitoring treatment effectiveness in patients diagnosed with VWD. The test helps in evaluating the functionality of von Willebrand factor (vWF) by measuring its ability to bind to platelets in the presence of the antibiotic ristocetin. Abnormal results may indicate VWD, a bleeding disorder caused by quantitative or qualitative defects of vWF.
Special Instructions
This test should be ordered in conjunction with von Willebrand Factor Antigen (0030285) and Factor VIII, Activity (0030095) for a comprehensive evaluation of suspected von Willebrand disease.
Limitations
The von Willebrand Factor Activity test may be affected by improper specimen handling and collection. Hemolyzed or clotted specimens can lead to inaccurate results, as can incorrect specimen volume. It is critical to follow proper specimen handling procedures as detailed in the hemostasis/thrombosis specimen handling guidelines. The presence of anticoagulants such as EDTA in the specimen may also affect the test results.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 6014-5
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1.5 mL
Minimum Volume
1 mL
Container
ARUP standard transport tube
Collection Instructions
Collect using a Lt. blue (sodium citrate) tube. Ensure platelet-poor plasma is transferred to the transport tube.
Causes for Rejection
Serum, EDTA plasma, clotted or hemolyzed specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Refrigerated | Unacceptable |
| Frozen | 3 months |
Other tests from different labs that may be relevant