Ristocetin Cofactor

Ristocetin Cofactor

## Ristocetin Cofactor

### Test Description
The Ristocetin Cofactor test, also known as von Willebrand Factor (vWF) activity – ristocetin cofactor test, is a blood test that evaluates the functioning of a protein called von Willebrand factor (vWF) that helps blood to clot. The test takes advantage of the ability of ristocetin to promote platelet agglutination in the presence of vWF. The test measures the ability of vWF to bind to platelets in the presence of ristocetin, which is a measure of the vWF activity.

### Indications of the Test
The test is used to diagnose von Willebrand disease (VWD), which is a bleeding disorder caused by a deficiency or dysfunction of vWF. The test is also used to monitor the treatment of VWD and to evaluate bleeding disorders that may be caused by other factors.

### Patient Preparation/Instructions
No special preparation is required for the test. However, patients should inform their doctor of any medications they are taking, as some medications can affect the test results.

### Typical Reference Values
The normal range of vWF activity is 50 to 200 IU/dL. A vWF activity level of less than 30% is designated as the level for a definitive diagnosis of VWD, although some patients with type 1 or type 2 VWD have vWF activity levels of 30-50%.

### Turnaround Time
The turnaround time for the test varies depending on the laboratory performing the test.

### Order This Test
To order the Ristocetin Cofactor test, click the “Order Test” button and add it to the cart.

Citations:
[1] Blood Test: von Willebrand Factor (vWF) Activity – Ristocetin Cofactor https://kidshealth.org/en/parents/test-vwf.html
[2] Ristocetin Cofactor (Functional von Willebrand Factor): Reference Range, Interpretation, Collection and Panels https://emedicine.medscape.com/article/2086190-overview
[3] Limitations of the Ristocetin Cofactor Assay in Measurement of VWF Function https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3825106/
[4] Diagnostic approach to von Willebrand disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4375103/
[5] von Willebrand Factor – Understand the Test https://www.testing.com/tests/von-willebrand-factor/