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Difficulty: EasyMonitoring and Treatment Evaluation

A 64-year-old man is hospitalized for an acute deep vein thrombosis of the right lower extremity. He is promptly started on a continuous unfractionated heparin infusion. On admission (hospital day 1), his platelet count is 240,000/mm³. On hospital day 5, routine morning laboratory studies reveal a platelet count of 90,000/mm³. The patient remains hemodynamically stable, reports no new symptoms, and physical examination reveals no petechiae, ecchymoses, or signs of active bleeding. His right leg swelling has improved. Which of the following is the most appropriate next step in the management of this patient?

  1. Discontinue the unfractionated heparin and initiate an argatroban infusionAnswer
  2. B
    Continue the current unfractionated heparin infusion and monitor daily platelet counts
  3. C
    Discontinue the unfractionated heparin and initiate therapeutic enoxaparin
  4. D
    Discontinue the unfractionated heparin and initiate warfarin
  5. E
    Transfuse one unit of apheresis platelets

Answer

Discontinue the unfractionated heparin and initiate an argatroban infusion
The correct answer correctly identifies that a >50% drop in platelet count occurring 5 to 10 days after the initiation of unfractionated heparin is highly suspicious for Heparin-Induced Thrombocytopenia (HIT). The most critical initial step in managing suspected HIT is the immediate discontinuation of all heparin products. Furthermore, because HIT is a highly prothrombotic state, patients require immediate anticoagulation with a non-heparin agent, such as a direct thrombin inhibitor (argatroban or bivalirudin) or fondaparinux, to prevent life-threatening thrombotic complications.

Step-by-Step Solution

1
Evaluate the change in platelet count relative to the timeline of heparin administration.
The platelet count dropped from 240,000 to 90,000 (a >50% decrease) occurring on hospital day 5.
This specific timing and magnitude of platelet drop is the classic hallmark of Type II Heparin-Induced Thrombocytopenia (HIT).
2
Determine the necessary treatment modification based on the suspected diagnosis of HIT.
All heparin products must be stopped, and a non-heparin anticoagulant must be started.
HIT is a highly prothrombotic state caused by antibodies to the heparin-PF4 complex. A direct thrombin inhibitor like argatroban is required to prevent catastrophic thrombosis while the platelet count recovers.

Key Concept

Monitoring for and managing Heparin-Induced Thrombocytopenia (HIT)
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Topics

Monitoring and Treatment Evaluation

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