Table 1.
Screening assays for VWD and expected results for each type
| Assay | Type 1 | Type 2A | Type 2B | Type 2M | Type 2N | Type 3 | Reference range |
|---|---|---|---|---|---|---|---|
| VWF:Ag | Low | Low | Low | Normal/low | Normal/low | Undetectable | 50‐240 IU/dL |
| VWF:GPIbMa or VWF:RCoa | Low | Very low | Very low | Low | Normal/Low | Undetectable | 50‐240 IU/dL |
| VWF:GPIbM/VWF:Ag or VWF:RCo/VWF:Ag | Normal | Low | Low | Low | Normal | – | >0.6 |
| VWF:CB | Low | Very low | Very low | Normal/low | Normal/low | Undetectable | 50‐240 IU/dL |
| VWF:CB/VWF:Ag | Normal | Low | Low | Normal/low | Normal | – | >0.6 |
| FVIII:C | Normal/low | Normal/low | Normal/low | Normal/low | Very low | Very low | 60‐190 IU/dL |
| FVIII:C/VWF:Ag | Normal | Normal | Normal | Normal | Low | – | >0.7 |
FVIII:C, factor VIII; VWF, von Willebrand factor; VWF:Ag, VWF antigen; VWF:CB, VWF collagen binding; VWF:GPIbM, VWF binding to mutant (gain of function) GPIb; VWF:RCo, VWF ristocetin cofactor activity
a
VWF:GPIbM has replaced the VWF:RCo in some centers, but VWF:RCo or any VWF platelet‐dependent activity assay could be used here as well.