von Willebrand factor multimers

Last updated: Thursday, 25, March, 2004

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Item Process
Specimen

4.5 mL blood added to 0.5 mL citrate or 5 mL blood in EDTA.

Method

Crossed immunoelectrophoresis; SDS-agarose electrophoresis with autoradiography or enzyme-linked antibody staining.

Application

Characterisation of patients with definite or highly probable von Willebrand’s disease into subtypes (that is, 1, 2, 3 or platelet-type VWD).

May also be useful when assessing VWD defects of genetic significance and as a guide to management.

Multimers are not used as a screening test for von Willebrand disease.

Interpretation

The findings are interpreted together with the personal and family history, and the levels of VWF by quantitative assays.
See von Willebrand factor antigenRistocetin cofactor and Collagen binding assay.

Type 1 VWD is a quantitative disorder of VWF (usually desmopressin responsive). These patients have normal VWF multimeric profiles but a lower overall intensity of apparent VWF by multimer testing, depending on the severity of the disorder.

Type 3 VWD (desmopressin unresponsive) is a total quantitative disorder of VWF and these patients generally have VWF undetectable by multimeric profile.
Type 3 VWD is a severe bleeding disorder in which VWF is typically absent from plasma (or present only in trace amounts); desmopressin is ineffective.

In Type 2 VWD there is an abnormality in the multimeric structure of VWF leading to reduced (ristocetin-induced) binding to platelets (Type 2A) or enhanced binding to platelets (Type 2B). Desmopressin responsiveness is variable in Type 2A.
Desmopressin may cause thrombocytopenia in Type 2B and is usually avoided.

In pseudo- or platelet-type VWD the large multimers of VWF are absent. Desmopressin and infusion of plasma are contraindicated as their use is associated with thrombocytopenia.

See also von Willebrand's disease, von Willebrand factor antigen (VWF:Ag), Ristocetin cofactor and Collagen binding assay.

Reference

Favaloro EJ. Clin Haematol 2001; 14: 299-319.

Sadler JE. Thromb Haemost 1994: 71; 520-525.