What is the role of activated partial thromboplastin time (aPTT) in the screening of pediatric von Willebrand disease (VWD)?

Updated: Feb 05, 2019
  • Author: Suchitra S Acharya, MD, MBBS; Chief Editor: Hassan M Yaish, MD  more...
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Approximately 25% of patients with type 1 von Willebrand disease have aPTT results outside of the reference range. These results may be caused by concurrent deficiencies of other clotting factors in addition to, or rather than, factor VIII (FVIII). The aPTT should be outside of the reference range in patients with severe von Willebrand disease or type 2N von Willebrand disease in whom circulating FVIII levels are very low. Because aPTT and the template bleeding time are insensitive tests for von Willebrand disease, add von Willebrand factor (VWF) activity to the screening tests performed for patients with suspected bleeding disorders (see below).

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