Von Willebrand Factor Ristocetin Cofactor Activity (vWF) Test
Short Name: vWF:RCo
Also known as: vWF:RCo, Von Willebrand Factor Ristocetin Cofactor, Ristocetin Cofactor Activity, vWF Activity
Von Willebrand Factor Ristocetin Cofactor Activity (vWF) Test test available at DNA Labs India for ₹13,000. Uses Chemiluminescent Immunoassay on Whole Blood samples. Results in For samples collected by 11 AM, reports are issued the same day by 6 PM. Samples collected later may be available the next day.. Free home collection in 300+ cities across India.
🩺 Medically Reviewed By
Dr SHAILAJA RAGHUNATH MURDESHWAR
Consultant Physician · Reg: 8052
Last reviewed: September 7, 2026
Overview
The vWF:RCo assay determines the activity of von Willebrand factor (vWF) plasma protein and is used for the basic screening of von Willebrand disease (vWD). vWF plays a key role in primary and secondary hemostasis, serving as a carrier protein for factor VIII. vWD is the most common inherited bleeding disorder, characterized by easy bruising and prolonged bleeding from mucosal surfaces. The vWF:RCo test is used along with factor VIII activity and vWF:Ag for the basic screening of von Willebrand disease. This test helps doctors assess the platelet-binding function of vWF and is essential in the diagnosis and classification of vWD.
- Test Code
- 3754
- ICD Code
- D68.0
- Price
- ₹13,000
- Sample Type
- Whole Blood
- Result Time
- For samples collected by 11 AM, reports are issued the same day by 6 PM. Samples collected later may be available the next day.
- Fasting Required
- No
- Method
- Chemiluminescent Immunoassay
Sample Collection
Overnight fasting is preferred, though not mandatory. Avoid strenuous exercise for 24 hours prior to testing. Duly filled Coagulation Requisition Form (Form 15) is mandatory. Inform your doctor about all medications, supplements, and any recent bleeding or transfusions.
Method: Venipuncture
Laboratory Analysis
A trained phlebotomist will collect 3 mL of whole blood into a blue top (sodium citrate) tube. The tube should be mixed thoroughly by gentle inversion to prevent clotting.
Report Delivery
Apply firm pressure to the puncture site to minimise bruising. The sample must be transported to the laboratory within 4 hours. If transport is delayed, the laboratory will prepare platelet-poor plasma (PPP) within 1 hour of collection and freeze it at -20°C or below. Do not thaw the frozen sample before testing.
Timeline: For samples collected by 11 AM, reports are issued the same day by 6 PM. Samples collected later may be available the next day.
Patient Instructions
About This Test
Who Should Get This Test
The vWF:RCo assay determines the activity of von Willebrand factor (vWF) plasma protein and is used for the basic screening of von Willebrand disease (vWD). vWF plays a key role in primary and secondary hemostasis, serving as a carrier protein for factor VIII. vWD is the most common inherited bleeding disorder, characterized by easy bruising and prolonged bleeding from mucosal surfaces. The vWF:RCo test is used along with factor VIII activity and vWF:Ag for the basic screening of von Willebrand disease. This test helps doctors assess the platelet-binding function of vWF and is essential in the diagnosis and classification of vWD.
How to Prepare
- Use 1 Blue Top (Sodium Citrate) tube and fill exactly 3 mL
- Mix thoroughly by inversion immediately after collection
- Transport to Lab within 4 hours at room temperature
- If transport delayed, centrifuge sample at 3600 rpm for 15 minutes and transfer supernatant to a clean plastic tube
- Centrifuge the supernatant again at 3600 rpm for 15 minutes
- Transfer final supernatant (PPP) to a labelled plastic screw-capped vial and freeze immediately
- Ship frozen. Do not thaw. Duly filled Coagulation Requisition Form (Form 15) is mandatory
Doctor's Notes
Reviewed by Dr SHAILAJA RAGHUNATH MURDESHWAR — MBBS, MD (General Medicine) · Reg. No. 8052
"In patients with a suspected bleeding disorder, vWF:RCo is a key functional assay. Reduced activity with a normal or low antigen level helps classify von Willebrand disease."
Last medically reviewed: September 7, 2026
Test Parameters & Specifications
Sample Stability
- Clotted sample
- Sample received after more than 4 hours at room temperature (if not separated)
- Thawed frozen sample
- Insufficient volume or improper filling of citrate tube
- Hemolyzed or grossly lipemic specimen
- Missing or incorrectly filled requisition form
Understanding Your Results
vWF:RCo 50-200 IU/dL
No evidence of vWF activity defect
vWF:RCo 30-50 IU/dL
Possible type 1 vWD or acquired conditions; further correlation with vWF antigen and factor VIII required
vWF:RCo <30 IU/dL
Consistent with von Willebrand disease; subclassification requires vWF:Ag, factor VIII and multimers
Consult a doctor if you have unexplained bleeding, easy bruising, heavy menstrual periods, or a family history of bleeding disorders. A physician will determine whether a vWF:RCo test is appropriate based on your symptoms and clinical history.
Limitations
- ⚠vWF:RCo alone cannot differentiate all vWD subtypes; it should be combined with vWF:Ag and factor VIII tests
- ⚠The assay has lower sensitivity for certain borderline deficiencies
- ⚠vWF levels vary with age, blood group, and endocrine factors
- ⚠Delayed sample processing can falsely lower activity
Risks & Considerations
- ●Minor bruising at the needle site
- ●Slight pain or discomfort during needle insertion
- ●Rare risk of infection
- ●Excessive bleeding is very unlikely
Interfering Factors
- ●Blood group O has lower baseline vWF levels
- ●Recent blood transfusion or desmopressin (DDAVP) therapy
- ●Pregnancy and oestrogen therapy can increase vWF levels
- ●Stress or acute physical activity can raise vWF
- ●Improper sample collection or inadequate mixing of citrate tube
- ●Haemolysis or lipemia in the sample
Frequently Asked Questions
What is the vWF:RCo test?
Why is the vWF:RCo test done?
How is the vWF:RCo test performed?
Do I need to fast before the vWF:RCo test?
What is the cost of the vWF:RCo test at DNA Labs India?
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Is home sample collection available for this test?
What does a low vWF:RCo level mean?
Can von Willebrand disease be diagnosed by vWF:RCo alone?
What is the normal range for vWF:RCo?
Can I do this test while pregnant?
How often should the vWF:RCo test be repeated?
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