Heparin-Induced Thrombocytopenia (HIT)

Hematology

Overview

Definition

Prothrombotic disorder caused by antibodies to Heparin-PF4 complex.

Epidemiology

Varies globally depending on genetics, environment, or exposure.

Etiology & Risk Factors

  • Exposure to Unfractionated Heparin (typically 5-10 days later).

Clinical Symptoms

  • Drop in platelet count by >50%
  • paradoxical arterial or venous thrombosis (DVT/PE).

Clinical Approach

Diagnosis

  • 4T Score
  • PF4 ELISA
  • Serotonin Release Assay (SRA).

Management

  • STOP all heparin IMMEDIATELY
  • start direct thrombin inhibitor (Argatroban
  • Bivalirudin).

Complications

  • Limb gangrene
  • Stroke
  • PE.