Department of Haematology

Notes

A full von Willebrand's investigation consist of the following assays:

  • Clotting Screen  (performed at GRH or CGH)
  • Factor VIII assay  (performed at GRH, CGH or Oxford Haemophilia Centre)
  • Ristocetin Co-Factor (Ricof) Assay (performed at Oxford Haemophilia Centre)
  • von Willebrand Factor - Collagen Binding Assay (performed at Oxford Haemophilia Centre)

The von Willebrand Collagen Binding Assay consists of 2 tests:

  • von Willebrand Factor - Collagen Binding Assay (CBA)
  • von Willebrand Antigen test.

Sample Requirements

3 x 3ml or 3.5ml Trisodium Citrate samples (for Clotting Screen, Factor VIII, Ricof and von Willebrands assays)

 

x 3

3ml Trisodium citrate

 

Turnaround Times

Up to 6 weeks for all investigations to be completed

Sample Storage and Retention

  • Pre analysis storage: do not store, send to laboratory within 2 hours.
  • Sample retention by lab: Citrate samples are retained for a minimum of 24 hours at 15-30°C. If specialist coagulation tests are requested, one or more aliquots may be frozen until analysis (or up to two months) at between -15 and -40°C. After analysis, these samples will be retained for a further 24 hours at 15-30°C.

It may be possible to add these tests on to a previous request as long as there were sufficient samples and the samples are less than 4 hours old (if not already frozen).

Reference Ranges

Please click for Clotting Screen and Factor VIII ranges.

Assay Range Units
von Willebrand - Collagen Binding Assay 50 - 200 iu/dl
von Willebrand Antigen Test 50 - 200 iu/dl
Ristocetin Co-Factor 50 - 150 %

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von Willebrand's Factor Investigations

Department of Haematology

Notes

A full von Willebrand's investigation consist of the following assays:

  • Clotting Screen  (performed at GRH or CGH)
  • Factor VIII assay  (performed at GRH, CGH or Oxford Haemophilia Centre)
  • Ristocetin Co-Factor (Ricof) Assay (performed at Oxford Haemophilia Centre)
  • von Willebrand Factor - Collagen Binding Assay (performed at Oxford Haemophilia Centre)

The von Willebrand Collagen Binding Assay consists of 2 tests:

  • von Willebrand Factor - Collagen Binding Assay (CBA)
  • von Willebrand Antigen test.

Sample Requirements

3 x 3ml or 3.5ml Trisodium Citrate samples (for Clotting Screen, Factor VIII, Ricof and von Willebrands assays)

 

x 3

Citrate Sample

 

Turnaround Times

Up to 6 weeks for all investigations to be completed

Sample Storage and Retention

  • Pre analysis storage: do not store, send to laboratory within 2 hours.
  • Sample retention by lab: Citrate samples are retained for a minimum of 24 hours at 15-30°C. If specialist coagulation tests are requested, one or more aliquots may be frozen until analysis (or up to two months) at between -15 and -40°C. After analysis, these samples will be retained for a further 24 hours at 15-30°C.

It may be possible to add these tests on to a previous request as long as there were sufficient samples and the samples are less than 4 hours old (if not already frozen).

Reference Ranges

Please click for Clotting Screen and Factor VIII ranges.

 

AssayRangeUnitsvon Willebrand - Collagen Binding Assay50 - 200iu/dlvon Willebrand Antigen Test50 - 200iu/dlRistocetin Co-Factor50 - 150%

 

Decreased Ristocetin Co-Factor is associated with von Willebrand's Disease, with a result of <40% being considered suggestive of von Willebrand's Disease.

Decreased Ristocetin Co-Factor is associated with von Willebrand's Disease, with a result of <40% being considered suggestive of von Willebrand's Disease.

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