Differences between low VWF and type 1 VWD
| . | Low VWF . | Type 1 VWD . |
|---|---|---|
| Diagnosis | Plasma VWF levels consistently 30-50 IU/dL | Plasma VWF levels consistently <30 IU/dL |
| VWF gene sequence variations | Detected in 40% to 64% of patients | Detected in majority of patients (up to 91.8%) |
| Pathogenic mechanism | Predominantly due to reduced VWF synthesis/secretion within EC. Subtle enhanced clearance in some cases. | Depending upon VWF gene mutation, can be attributable to a major impairment in VWF synthesis and/or markedly enhanced VWF clearance (type 1C VWD) |
| Response to DDAVP | Consistent and reproducible plasma VWF responses, with levels sustained >50 IU/dL at 4 h | Variable responses, related to the nature of the underlying VWF mutation. Complete response, partial response, or failure to respond may be seen. In patients with type 1C VWD, VWF half-life may be <4 h. |
| Need for DDAVP trial | No need for routine DDAVP trial but confirm plasma VWF:Ag levels and duration of response at time of first therapeutic use | DDAVP trial should be performed and should include plasma samples at 4 h post-DDAVP to ensure no rapid fall-off in plasma VWF levels |
| Plasma VWF half-life | Some low VWF patients have elevated VWF:pp/VWF:Ag ratios consistent with subtly increased VWF clearance | Related to underlying VWF mutation, but patients with type 1C VWD may have markedly enhanced VWF clearance with half-lives <4 h |
| ABO effect | Blood group O is strongly overrepresented | The effect of ABO blood group is less significant |
| Impact of aging | Plasma VWF levels increase with age and often correct into the normal range (>50 IU/dL) | Depending on underlying VWF gene mutation, plasma VWF levels may increase with age, but often remain <50 IU/dL |
| Not clear whether age-related VWF correction necessarily equates to resolution of bleeding phenotype | Unknown whether age-related increase in plasma VWF levels attenuates bleeding risk |
| . | Low VWF . | Type 1 VWD . |
|---|---|---|
| Diagnosis | Plasma VWF levels consistently 30-50 IU/dL | Plasma VWF levels consistently <30 IU/dL |
| VWF gene sequence variations | Detected in 40% to 64% of patients | Detected in majority of patients (up to 91.8%) |
| Pathogenic mechanism | Predominantly due to reduced VWF synthesis/secretion within EC. Subtle enhanced clearance in some cases. | Depending upon VWF gene mutation, can be attributable to a major impairment in VWF synthesis and/or markedly enhanced VWF clearance (type 1C VWD) |
| Response to DDAVP | Consistent and reproducible plasma VWF responses, with levels sustained >50 IU/dL at 4 h | Variable responses, related to the nature of the underlying VWF mutation. Complete response, partial response, or failure to respond may be seen. In patients with type 1C VWD, VWF half-life may be <4 h. |
| Need for DDAVP trial | No need for routine DDAVP trial but confirm plasma VWF:Ag levels and duration of response at time of first therapeutic use | DDAVP trial should be performed and should include plasma samples at 4 h post-DDAVP to ensure no rapid fall-off in plasma VWF levels |
| Plasma VWF half-life | Some low VWF patients have elevated VWF:pp/VWF:Ag ratios consistent with subtly increased VWF clearance | Related to underlying VWF mutation, but patients with type 1C VWD may have markedly enhanced VWF clearance with half-lives <4 h |
| ABO effect | Blood group O is strongly overrepresented | The effect of ABO blood group is less significant |
| Impact of aging | Plasma VWF levels increase with age and often correct into the normal range (>50 IU/dL) | Depending on underlying VWF gene mutation, plasma VWF levels may increase with age, but often remain <50 IU/dL |
| Not clear whether age-related VWF correction necessarily equates to resolution of bleeding phenotype | Unknown whether age-related increase in plasma VWF levels attenuates bleeding risk |