Table 1.

Classification of VWD Based on Specific VWF Tests

VWD TypeVWF:Act 1VWF:Ag 1Act/AgFVIII:C IU/dL 1Multimer Pattern 2Other
1LowLowEquivalent~1.5x VWF:AgEssentially normal
2ALowLowVWF:Act < VWF:AgLow or normalAbnormal ↓ HMW↓ VWF:GP1BA binding
2BLowLowVWF:Act < VWF:AgLow or normalOften abnormal ↓ HMW↑ RIPA 3 (↓ platelet count)
2MLowLowVWF:Act << VWF:AgLow or normalNo loss of HMW↓ VWF:GP1BA binding
↓VWF:collagen binding 4
2NNormal/lowNormal/lowEquivalent<40Normal in most cases↓ VWF:FVIIIB 5
3AbsentAbsentNA<10Absent
1.

Relative to the reference range (approximate values); VWF:Act (50-200 IU/dL), VWF:Ag (50-200 IU/dL), FVIII:C (50-150 IU/dL). VWF activity (VWF:Act) includes VWF:RCo and the newer VWF activity assays in this instance.

2.

HMW multimers

3.

Increased agglutination at low concentrations of ristocetin

4.

Reduction in the ability of VWF to bind to collagen. Types I/III are bound by the A3 domain while types IV and VI are bound by the A1 domain. The latter types are not commonly analyzed.

5.

Ability of VWF to bind and protect FVIII is reduced. VWF and FVIII levels can look exactly like those in males with mild hemophilia A or in symptomatic hemophilia A carrier females.

From: von Willebrand Disease

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