Last reviewed: 25 Dec 2020
Last updated: 09 Apr 2019



History and exam

Key diagnostic factors

  • non-specific prodrome
  • severe neurological symptoms (coma, focal abnormalities, seizures)
  • mild neurological symptoms (headache, confusion)
  • fever

Other diagnostic factors

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

Risk factors

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

Diagnostic investigations

1st investigations to order

  • platelet count
  • haemoglobin
  • haptoglobin
  • peripheral smear
  • reticulocyte count
  • urinalysis
  • urea and creatinine
  • direct Coombs' test
More 1st investigations to order

Investigations to consider

  • ADAMTS-13 activity assay and inhibitor titres
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.


RFC declares that she has no competing interests.

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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