H1N1 influenza (swine flu)-associated thrombotic microangiopathy with a markedly high plasma ratio of von Willebrand factor to ADAMTS13

Intern Med. 2011;50(6):643-7. doi: 10.2169/internalmedicine.50.4620. Epub 2011 Mar 15.


We describe an 18-year-old woman infected with H1N1 influenza followed by thrombotic microangiopathy. During the acute phase, her plasma levels of von Willebrand factor (VWF) were remarkably elevated, whereas those of ADAMTS13 were reduced without its inhibitors, generating a markedly high ratio of VWF to ADAMTS13 in circulation. A retrospective analysis established the following hypothesis: an influenza-mediated cytokine storm induced an enhanced release of unusually large VWF multimers (UL-VWFM) from vascular endothelial cells, generating platelet thrombi in microcirculatures under high shear stress. Plasma exchange removed UL-VWFM and cytokines, and rescued her life. This report sheds a light on a hitherto unrecognized influenza complication.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / antagonists & inhibitors
  • ADAM Proteins / blood*
  • ADAMTS13 Protein
  • Adolescent
  • Female
  • Humans
  • Influenza A Virus, H1N1 Subtype*
  • Influenza, Human / blood*
  • Influenza, Human / complications
  • Influenza, Human / diagnosis
  • Retrospective Studies
  • Thrombotic Microangiopathies / blood*
  • Thrombotic Microangiopathies / diagnosis
  • Thrombotic Microangiopathies / etiology
  • von Willebrand Factor / biosynthesis
  • von Willebrand Factor / metabolism*


  • von Willebrand Factor
  • ADAM Proteins
  • ADAMTS13 Protein
  • ADAMTS13 protein, human