Von Willebrand Disease (VWD)
Part 1: NHLBI Diagnosis Guidelines
Introduction & Clinical Assessment Recommendations
Beyond Hot Topic is an opportunity for viewers to submit questions to the Hot Topic presenter. The opportunity to submit questions for this topic is now closed.
The following questions were submitted by viewers and answered by the presenter, William Nichols, MD, from the Division of Hematopathology at Mayo Clinic in Rochester, Minnesota. Questions are presented as submitted (unedited).
I'm sure you will get to it in part 2, but those that are "easy" to diagnose are easy. What do you do with the borderline cases with good histories or exam findings? Keep testing hoping to get an abnormal result?
Yes, test again in the absence of conditions associated with elevation of baseline VWF and factor VIII. Also, consider testing for other bleeding disorders, such as platelet hypofunction, etc. Also see part 2 presentation, including discussion of "borderline or mildly low VWF."
What about the affect of blood type, especially "O," what's low, what's borderline and what's OK?
Please see detailed discussion in part 2, concerning the impact of ABO blood group on VWF levels, bleeding symptoms and VWD diagnosis.
How reliable are the results you get from the lab? I assume all testing has an internal control for quality.
Short answer = "somewhat reliable..."! Testing quality issues are briefly discussed in part 2. There is need for improvement.
What if you have to ship the specimen, shouldn't it be frozen? If not frozen, how quickly do the proteins break down?
Please see part 2 where specific information is provided. Factor VIII coagulant activity is especially labile.
What about the significance of a history of more than 1 type of bleeding in the same patient?
As briefly discussed in part 1, an increasing number and type of bleeding symptoms or events increases the likelihood of having a bleeding disorder, such as VWD--and such information also informs about the clinical severity (e.g., mild, moderate, severe).
From the laboratory point of view, how can I suspect acquired VWS?
Acquired von Willebrand syndrome (AVWS) generally has no distinguishing laboratory features that differentiate AVWS from hereditary VWD. The clinical history assessment, including the presence or absence of medical conditions associated with AVWS, is paramount for differentiating between the 2. However, AVWS (or acquired von Willebrand factor abnormality = AVWA) caused by aortic valve stenosis (or similar conditions --see slide 9 in part 1) often has normal VWF levels, but subtle abnormalities of VWF multimers (loss of the very highest molecular weight multimers); such is not usually associated with hereditary VWD.