The 1st International Standard for von Willebrand Factor Concentrate: More to Come?

SummaryAn international study involving 26 laboratories assayed two candidate von Willebrand Factor (VWF) concentrates (B and C) for VWF:Antigen (VWF:Ag), VWF:Ristocetin Cofactor (VWF:RCo) and VWF:Collagen binding (VWF:CB) relative to the 4th International Standard Factor VIII/VWF Plasma (4th IS Plasma) (97/586). Estimates of VWF:Ag showed good agreement between different methods, for both candidates, and the overall combined means were 11.01 IU/ml with inter-laboratory variability (GCV) of 10.9% for candidate B and 14.01 IU/ml (GCV 11.8%) for candidate C. Estimates of VWF:RCo showed no significant difference between methods for both candidates and gave overall means of 9.38 IU/ml (GCV 23.7%) for candidate B and 10.19 IU/ml (GCV 24.4%) for candidate C. Prior to the calibration of the candidates for VWF:CB it was necessary to calibrate the 4th IS Plasma relative to local frozen normal plasma pools; there was good agreement between different collagen reagents and an overall mean of 0.83 IU per ampoule (GCV 11.8%) was assigned. In contrast, estimates of VWF:CB in both candidates showed large differences between collagen reagents with inter-laboratory GCV’s of 40%. Candidate B (00/514) was established as the 1st International Standard von Willebrand Factor Concentrate by the WHO Expert Committee on Biological Standardisation in November 2001 with assigned values for VWF:Ag (11.0 IU/ampoule) and VWF:RCo (9.4 IU/ampoule). Large inter-laboratory variability of estimates precluded the assignment of a value for VWF:CB.

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Value assignment of the WHO 2nd International Standard von Willebrand factor, concentrate (09/182)

Journal of Thrombosis and Haemostasis ◽

10.1111/j.1538-7836.2011.04365.x ◽

2011 ◽

Vol 9 (8) ◽

pp. 1638-1640 ◽

Cited By ~ 2

Author(s):

A. R. HUBBARD ◽

M. HAMILL ◽

M. BEEHARRY ◽

S. A. BEVAN ◽

A. B. HEATH ◽

...

Keyword(s):

Von Willebrand Factor ◽

Value Assignment ◽

International Standard ◽

Factor Concentrate ◽

Von Willebrand ◽

Willebrand Factor

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Successful management of multiple pregnancies in a family with varying severity of Von Willebrand disease

Obstetric Medicine ◽

10.1177/1753495x17754150 ◽

2018 ◽

Vol 11 (4) ◽

pp. 192-194

Author(s):

Patrick Harrington ◽

Pippa Kyle ◽

Jacky Cutler ◽

Bella Madan

Keyword(s):

Von Willebrand Factor ◽

Von Willebrand Disease ◽

The Other ◽

Severe Phenotype ◽

Mild Phenotype ◽

History Of ◽

Specialist Treatment ◽

Factor Concentrate ◽

Von Willebrand ◽

Willebrand Factor

We present the obstetric history of a family of three sisters with Von Willebrand disease, managed in our centre over the course of nine successful pregnancies. The abnormalities result from inheritance of an exon 50 skipping mutation in the Von Willebrand factor gene, resulting from consanguinity. Two of the sisters were identified as having a severe phenotype with a Von Willebrand factor level of less than 5 IU/dl, with the other having a mild phenotype. Of the sisters with a severe phenotype, one had a number of prenatal complications and required early onset prophylaxis with Von Willebrand factor concentrate, whilst the other had a less complicated clinical course, only requiring Von Willebrand factor concentrate to cover labour. The sister with mild Von Willebrand disease had a rise in Von Willebrand factor levels during pregnancy and required no specialist treatment. The report highlights the markedly different clinical courses that can occur in patients with Von Willebrand disease and the different approaches to management.

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Spontaneous pyohaemothorax in a teenager with von Willebrand disease: a case report and review of literature

BMJ Case Reports ◽

10.1136/bcr-2021-241613 ◽

2021 ◽

Vol 14 (8) ◽

pp. e241613

Author(s):

Vaishnavi Divya Nagarajan ◽

Asha Shenoi ◽

Lucy Burgess ◽

Vlad C Radulescu

Keyword(s):

Case Report ◽

Von Willebrand Factor ◽

Von Willebrand Disease ◽

Surgical Drainage ◽

Review Of Literature ◽

History Of ◽

Factor Concentrate ◽

Type 3 ◽

Von Willebrand ◽

Willebrand Factor

An 18-year-old man with a history of type 3 von Willebrand disease (VWD) presented with a spontaneous pyohaemothorax. Type 3 VWD may present with both mucocutaneous and deep-seated bleeds, such as visceral haemorrhages, intracranial bleeds and haemarthrosis. There have been very few cases described in children of spontaneous pyohaemothorax. Management of this patient was challenging due to risks of bleeding following surgical drainage, requiring constant replacement with von Willebrand factor concentrate, while monitoring factor VIII levels to balance the risks of thrombosis.

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