Abstract Number: PB1561
Meeting: ISTH 2020 Congress
Background: The term low von Willebrand factor (VWF) is referred to patients with VWF levels of 30-50 IU/dL. Diagnosis and management of patients with low VWF levels is clinically challenging.
Aims: To determine the clinical and phenotypic features of patients with low VWF.
Methods: We evaluated 29 patients with low VWF levels (VWF:Ag and/or VWF:RCo in the range of 30-50 IU/dL) and compared them with 36 VWD patients and 25 healthy control. All subjects underwent a panel of VWF tests, including VWF activity (VWF:RCo and VWF:CB), VWF:Ag, FVIII:C, RIPA and blood group typing. The ISTH Bleeding Assessment Tool (BAT) was assessed for each subject and was considered abnormal if BS was >3 for males or >5 for females.
Results: Demographic characteristics of the study population are summarized in Table 1. In patients with low VWF the mean of VWF:Ag was 47 IU/dL and VWF:RCo was 33 IU/dL and were significantly lower than control (114 IU/dL; P < .0001 and 116 IU/dL; P < .0001 respectively). In comparison to healthy control the median of BS in patients with low VWF was significantly higher (6.5 vs. 1.96; P < .0001) but was not significantly different from VWD patients (Table 2). 73% of female patients with low VWF had the experience of menorrhagia. Albeit significant bleeding in low VWF patients and reduced FVIII:C levels compared with controls (mean 65 IU/dL vs. 114 IU/dL; P < .0002), FVIII:C were normal in 83% of our low VWF cohort. FVIII:C/VWF:Ag ratios were significantly increased in low VWF levels patients as well as VWD patients compared with controls (P < .0002) that represent decreased VWF synthesis and/or secretion.
Conclusions: Our findings showed that low VWF levels can be associated with significant bleeding and patients should be considered as having a mild bleeding disorder rather than having a risk factor for bleeding.
|Subjects||N||Median age years||Blood group (O/non-O)||Gender (male/female)|
[Table 1 characteristics of the study population]
|Variable||Low VWF (n: 29)||VWD (n:36)||Healthy control (n:25)|
[Table 2 Median (range) of laboratory results]
To cite this abstract in AMA style:Seidi Zadeh O, Ahmadinejad M, Mojtabavi M, Homayoun S. Clinical and Phenotypic Evaluation of Patients with Low von Willebrand Factor [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/clinical-and-phenotypic-evaluation-of-patients-with-low-von-willebrand-factor/. Accessed January 28, 2022.
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