Heparin-induced thrombocytopenia

Background

• Despite low plt count pt is actually hypercoagulable; bleeding is unusual
• Pathophysiology
  • Pathologic activation / consumption of platelets due to Ab against heparin-plt complex
  • Activated platelets then cause blood clot formation
    • Platelet count falls b/c plts are bound in clots
  • Can be caused by unfrationated or LMWH (10x common in the former)
    • Occurs in 0.5-5% of pts tx'd w/ heparin
• Thrombosis occurs in 35-75% of pts; 20-30% die w/in 1 month

Clinical Features

• Typical
  • Symptoms begin 5-10d after initiation of heparin
    • >50% decrease in plt count (median nadir is ~60K; rarely <20K)
    • DVT or PE
    • Cerebral vein or adrenal vein thrombosis
    • Limb arterial occlusion
    • CVA
    • MI
    • Skin necrosis
• Rapid onset
  • Symptoms begin within hours of initiation of heparin
    • Due to preexisting circulating antibody from sensitization several weeks earlier
    • Sudden drop in plt count
    • Thrombosis
    • Flushing
    • Tachycardia
    • Hypotension
    • Dyspnea
• Delayed onset
  • Symptoms begin several days after heparin stopped
  • Severe thromboses

Treatment

1. Discontinue all heparin products
2. Do not give platelts (may precipitate thrombosis)
3. Start anticoagulation
   1. Consider lepirudin, argatroban, danaparoid, fondaparinux, bivalirudin
   2. Avoid warfarin

See Also

• Heparin (Unfractionated)
• Low Molecular Weight Heparin

Dispostion

• Admit

Source

Tintinalli