Last reviewed: June 2020
Last updated: April  2019



History and exam

Key diagnostic factors

  • nonspecific prodrome
  • severe neurologic symptoms (coma, focal abnormalities, seizures)
  • mild neurologic symptoms (headache, confusion)
  • fever

Other diagnostic factors

  • age 30 to 50 years
  • digestive symptoms (nausea, vomiting, diarrhea, abdominal pain)
  • weakness
  • bleeding symptoms (purpura, ecchymosis, menorrhagia)

Risk factors

  • black ethnicity
  • female gender
  • obesity
  • pregnancy (near term or postpartum period)
  • cancer therapies
  • HIV infection
  • bone marrow transplantation
  • antiplatelet agents
  • quinine

Diagnostic investigations

1st investigations to order

  • platelet count
  • hemoglobin
  • haptoglobin
  • peripheral smear
  • reticulocyte count
  • urinalysis
  • BUN and creatinine
  • direct Coombs test
More 1st investigations to order

Investigations to consider

  • ADAMTS-13 activity assay and inhibitor titers
More investigations to consider

Treatment algorithm


Associate Professor of Medicine

Division of Hematology and Medical Oncology

The University of Tennessee Health Science Center




SKR has received honoraria, speaker's fees, consultancy fees, and research support from Alexion Inc., Biogen, Octapharma, Baxalta, and Kedrion.

Dr Sandeep K. Rajan would like to gratefully acknowledge Dr Rebecca Fischer Connor, a previous contributor to this topic.

Peer reviewersVIEW ALL

George Lynn Cross Professor

Department of Biostatistics and Epidemiology

University of Oklahoma Health Sciences Center

Oklahoma City



JNG declares that he has no competing interests.

Associate Professor of Medicine

Department of Internal Medicine

Innsbruck Medical University




CP declares that he has no competing interests.

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