Heparin-induced thrombocytopenia

Last reviewed: 25 Feb 2023
Last updated: 06 May 2020



History and exam

Key diagnostic factors

  • presence of risk factors
  • history of recent heparin exposure
  • history of HIT
  • absence of conditions and medications that cause thrombocytopenia
  • history of recent surgery or trauma
  • features consistent with recent venous or arterial thromboembolic event (e.g., PE, DVT, stroke, MI)
  • necrosis at heparin injection site(s)
More key diagnostic factors

Other diagnostic factors

  • absence of bleeding
  • signs of adrenal haemorrhagic necrosis
  • acute systemic reaction
  • signs of venous limb gangrene
Other diagnostic factors

Risk factors

  • recent heparin exposure (within past 100 days)
  • recent orthopaedic or cardiovascular surgery
  • female sex
More risk factors

Diagnostic investigations

1st investigations to order

  • FBC
More 1st investigations to order

Investigations to consider

  • Warkentin (4Ts) Probability Scale
  • HIT antigen assay
  • HIT functional assay
  • coagulation studies
  • venous Doppler ultrasound
  • computed tomography pulmonary angiogram (CTPA)
  • ventilation-perfusion scan (V/Q scan)
  • cerebral computed tomography venogram
  • magnetic resonance venography (head)
More investigations to consider

Treatment algorithm


suspected HIT with 4Ts score of ≥4, or confirmed HIT

suspected HIT with 4Ts score ≤3


platelet recovery



Lori-Ann Linkins, MD, MSc(Clin Epi), FRCPC

Associate Professor

Department of Medicine

McMaster University

Thrombosis Consultant

Juravinski Hospital and Cancer Centre





LL is an author of several references cited in this topic. LL has received consulting fees from Janssen for data adjudication for a clinical trial. Janssen distributes rivaroxaban, which is mentioned as a treatment option for HIT.

Peer reviewers

Jeffrey S. Wasser, MD

Assistant Clinical Professor of Medicine

Acting Associate Chair of the Division of Hematology and Medical Oncology

University of Connecticut School of Medicine




JSW declares that he has no competing interests.

Henry Watson, MD, FRCP, FRCPath

Consultant Haematologist

Aberdeen Royal Infirmary

Foresterhill Health Campus




HW declares that he has no competing interests.

Simon Davidson, MPhil

Clinical Scientist

Royal Brompton Hospital

Honorary Clinical Lecturer

Imperial College London




SD is a consultant for Mitsubishi Pharma, the manufacturer of argatroban.

  • Heparin-induced thrombocytopenia images
  • Differentials

    • Postoperative state
    • Thrombotic thrombocytopenic purpura
    • Drug-induced thrombocytopenic purpura
    More Differentials
  • Guidelines

    • Guidelines for management of venous thromboembolism: heparin-induced thrombocytopenia
    • Diagnosis and management of heparin-induced thrombocytopenia (HIT)
    More Guidelines
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