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Von Willebrand Disease (VWD)
Part 2: NHLBI Diagnosis Guidelines

Laboratory Recommendations

VWD NHLBI Guidelines (2008) "Low VWF" versus "VWD Type 1"

Slide 15

May 2011

This slide summarizes rationale for distinguishing between "low VWF" and "VWD type 1" (as initially elaborated in the cited 2003 article by Sadler). Low VWF is common – for example, using typical 2 SD (standard deviation) reference ranges for VWD laboratory test results, about 2.5% of apparently normal persons would have levels somewhat below the lower level cutoff. Bleeding symptoms are common, even in apparently normal persons, with a prevalence up to 25 to 50% (see Part 1 discussion, slide 16). Therefore, low VWF and bleeding symptoms can be coincidentally associated (possibly as much as 10% or more). Mildly low VWF (just below the reference range) is believed to confer only modest risk of bleeding. Caution is therefore advised in diagnosing type 1 VWD, especially with mildly or borderline low levels, and in the absence of an abnormal bleeding history.

"Low VWF" versus "VWD Type 1"


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