Departments of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
Hematology Am Soc Hematol Educ Program. 2009:106-12. doi: 10.1182/asheducation-2009.1.106.
A sufficiently low level of von Willebrand factor (VWF) predisposes to bleeding that can be quite serious, and low VWF is a diagnostic feature of von Willebrand disease (VWD) type 1, which is characterized by partial quantitative deficiency of VWF. Recent groundbreaking studies of patients with VWD type 1 have delineated several pathophysiologic mechanisms that determine the plasma concentration of VWF, but the relationship between VWF level and the likelihood of bleeding remains less well understood. In part, this problem reflects the broad range of VWF levels in the population, so that the distinction between "normal" and "low" is arbitrary. The risk of bleeding certainly increases as the VWF level decreases, but the relationship is not very strong until the VWF level is very low. Furthermore, mild bleeding symptoms are common in apparently healthy populations and have many causes other than defects in VWF, which can make it impossible to attribute bleeding to any single factor, such as low VWF. These difficulties might be resolved by an epidemiologic approach to VWF and other risk factors for bleeding, analogous to how physicians manage multiple risk factors for cardiovascular disease or venous thromboembolism.
血管性血友病因子（VWF）水平过低可导致严重出血，这是血管性血友病（VWD）1 型的一个诊断特征，其特点是 VWF 部分数量缺乏。最近对 VWD 1 型患者的突破性研究描绘了几个决定 VWF 血浆浓度的病理生理机制，但 VWF 水平与出血可能性之间的关系仍不太清楚。部分原因是人群中 VWF 水平范围较广，因此“正常”和“低”之间的区分是任意的。VWF 水平越低，出血的风险肯定越大，但直到 VWF 水平非常低，这种关系才不是很强。此外，轻度出血症状在看似健康的人群中很常见，其原因有很多，不仅仅是 VWF 缺陷，这使得将出血归因于任何单一因素（如 VWF 水平低）变得不可能。通过对 VWF 及其他出血风险因素进行流行病学研究，可以解决这些困难，类似于医生如何管理心血管疾病或静脉血栓栓塞的多种风险因素。
