Ristocetin Cofactor Test – Reference Range(s)

The normal range of ristocetin cofactor test is between 42-200 %.

Interpretation of VWF test results can be challenging and may require consultation with a doctor who specializes in bleeding disorders, such as a hematologist or coagulation specialist, especially when determining subtypes.

People who have mild VWD may have normal VWF antigen and VWF activity test results, and people who do not have VWD may have moderately decreased test results. Using VWF antigen results along with the VWF activity and factor VIII coagulant activity give the optimal combination for diagnosis and management.

If the VWF antigen test is normal or nearly normal and the VWF activity is decreased, then the person may have Type 2 VWD. Further testing will be required to determine which subtype is present.

If no or very little VWF and factor VIII are present, then the person may have Type 3 VWD. This will typically be seen in a child who experiences bleeding episodes early in life. It may appear to be due (or actually be due) to hemophilia A, a factor VIII deficiency bleeding disorder that affects males.

Increased concentrations of VWF antigen and VWF activity are not considered diagnostic. VWF is one of many acute phase reactants. This means that levels will be temporarily increased with infections, inflammation, trauma, and with physical and emotional stressors. They are also increased with pregnancy and with the use of estrogen medications such as oral contraceptives.

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.