A series of coagulation tests to diagnose Von Willebrands disease
Tube
05 (CP) – Citrate
ID
12707
Availability
24/7
Additional Information
Tests include prothrombin time (PT), APTT, Fibrinogen, FVIII assay, VWF antigen assay and Ristocetin co-factor activity.
PLEASE NOTE from October 2025 the vW ristocetin cofactor assay will be replaced by the vW activity (GP1b-R) assay performed on an Acustar analyser.
Turn Around
2 hours if urgent. 14 days routine.
Send to
Specialist Coagulation
Centre for Laboratory Medicine
St James University Hospital
Beckett Street
Leeds
LS9 7TF
Contact
Collection Con
2 x citrate samples. All citrate tubes must be filled to the line please. Samples must be processed within 6 hours of being taken.
Sample Type
Blood
Sample Storage
Citrated plasma. Must be processed or plasma frozen within 6 hours of collection.
Ref. Range (Male)
Factor VIII 50.0 – 150.0. vW antigen 50.2 – 153.8. Acustar vW Activity (GP1b-R) 45.6 – 176.3.
Ref. Range (Female)
Factor VIII 50.0 – 150.0. vW antigen 50.2 – 153.8. Acustar vW Activity (GP1b-R) 45.6 – 176.3.
Ref. Range (Paed)
Factor VIII 50.0 – 150.0. vW antigen 50.2 – 153.8. Acustar vW Activity (GP1b-R) 45.6 – 176.3. Please note that these are adult reference ranges and may not apply to patients <12 months old. Interpretation of results must always be done in light of the clinical setting.
Reference Range Notes
Critical telephone values: Any abnormal result if the clinical details state acute bleeding. Ristocetin co-factor less than 10%
Units
IU/dL
Turnaround Times
IP Acute TAT – 2 hours
IP Routine TAT – 14 days