von Willebrand factor (VWF) is a large adhesive multimeric protein involved in hemostasis. The larger the size (or number of VWF multimers), the greater the functionality of the protein. A deficiency or defect of VWF can lead to von Willebrand disease (VWD) and cause bleeding. Conversely, an increase in VWF may create an environment that promotes thrombosis. ADAMS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), sometimes called VWF-cleaving protease, is primarily responsible for controlling the size of VWF. The most severe deficiency (<10% of normal levels) of ADAMTS-13 arises in thrombotic thrombocytopenic purpura, a condition characterized by the presence of ultralarge VWF and clinically resulting in enhanced risk of thrombosis. However, ADAMTS-13 deficiency may result from other pathological processes. Of relevance is the recent finding that COVID-19 (coronavirus disease 2019) is associated with both increased levels and activity of VWF as well as generally decreased (or occasionally normal) activity levels of ADAMTS-13. Thus, in COVID-19 there is an alteration in the VWF/ADAMTS-13 axis, most often described by increased VWF/ADAMTS-13 ratio (or reduced ADAMTS-13/VWF ratio). COVID-19 is also associated with high prothrombotic risk. Thus, the imbalance of VWF and ADAMTS-13 in COVID-19 may be providing a milieu that promotes (micro)thrombosis, in a clinical picture resembling a secondary thrombotic microangiopathy in some patients. This review therefore assesses the literature on VWF, ADAMTS-13, and COVID-19. Whenever reported in COVID-19, VWF has always been identified as raised (compared with normal reference ranges or control populations). Reports have included VWF level (i.e., VWF antigen) and in some cases one or more VWF “activity” (e.g., collagen binding; platelet glycoprotein Ib [GPIb] binding, using ristocetin cofactor or more modern versions including VWF:GPIbR [recombinant] and VWF:GPIbM [mutant]). Whenever reported, ADAMTS-13 has been reported as “normal” or reduced; however, it should be recognized that “normal” levels may still identify a relative reduction in individual cases. Some reports also discuss the raised VWF/ADAMTS-13 (or reduced ADAMTS-13/VWF) ratio, but very few provide actual numerical data.

血管性血友病因子（VWF）是一种参与止血的大型粘性多聚体蛋白。大小（或VWF多聚体数目）越大，蛋白质的功能越强。VWF的缺乏或缺陷会导致von Willebrand病（VWD）并引起出血。相反，VWF的增加可能会形成促进血栓形成的环境。ADAMS-13（一 d isintegrin一个第二米与etalloproteinase吨hrombo小号pondin 1型基序，部件13），有时称为VWF裂解蛋白酶，主要负责控制VWF的大小。ADAMTS-13的最严重缺陷（<正常水平的10％）出现在血栓性血小板减少性紫癜中，这种疾病的特征是存在超大型VWF，临床上导致血栓形成的风险增加。但是，ADAMTS-13缺乏症可能是由其他病理过程引起的。与此相关的是最近的发现，即COVID-19（2019年冠状病毒病）与VWF的水平和活性升高以及ADAMTS-13的活性水平普遍降低（或偶尔正常）有关。因此，在COVID-19中，VWF / ADAMTS-13轴发生变化，通常以增加的VWF / ADAMTS-13比率（或降低的ADAMTS-13 / VWF比率）描述。COVID-19还与高血栓形成风险相关。因此，在类似于某些患者继发性血栓性微血管病的临床表现中，COVID-19中VWF和ADAMTS-13的失衡可能提供了促进（微）血栓形成的环境。因此，本综述评估了有关VWF，ADAMTS-13和COVID-19的文献。每当在COVID-19中报告时，始终将VWF识别为升高（与正常参考范围或对照人群相比）。报告包括VWF水平（即VWF抗原），在某些情况下还包括一种或多种VWF“活性”（例如胶原蛋白结合；使用瑞斯托霉素辅因子或更现代的版本，包括VWF：GPIbR [重组]结合血小板糖蛋白Ib [GPIb]）和VWF：GPIbM [mutant]）。无论何时报告，ADAMTS-13均被报告为“正常”或降低；然而，应该认识到，“正常”水平仍然可以确定个别情况的相对减少。一些报告还讨论了提高的VWF / ADAMTS-13（或降低的ADAMTS-13 / VWF）比率，但是很少提供实际的数值数据。