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Zorluk: OrtaHematology and Oncology

A 58-year-old man is evaluated on hospital day 6 for new-onset right lower extremity swelling and pain. He was admitted 6 days ago for a severe exacerbation of chronic obstructive pulmonary disease and has been receiving intravenous corticosteroids, bronchodilators, and subcutaneous unfractionated heparin for deep vein thrombosis prophylaxis. His respiratory status has significantly improved, but today he reports worsening right calf pain. Vital signs are temperature 37.2°C (99.0°F), blood pressure 130/80 mmHg, pulse 92/min, and respirations 16/min. Physical examination shows a swollen, erythematous, and tender right calf. Laboratory studies from today show a hemoglobin of 13.2 g/dL, leukocyte count of 8,500/mm³, and platelet count of 90,000/mm³. His platelet count on admission was 240,000/mm³. A lower extremity venous duplex ultrasound reveals a noncompressible right popliteal vein. Which of the following is the most appropriate next step in management?

  1. A
    Transfuse platelets and discontinue unfractionated heparin
  2. B
    Discontinue unfractionated heparin and initiate enoxaparin
  3. Discontinue unfractionated heparin and initiate argatrobanCevap
  4. D
    Continue unfractionated heparin and obtain a serotonin release assay
  5. E
    Discontinue unfractionated heparin and initiate warfarin

Cevap

Discontinue unfractionated heparin and initiate argatroban
The correct answer is to discontinue unfractionated heparin and initiate argatroban. This patient has developed Heparin-Induced Thrombocytopenia (HIT) Type 2, characterized by a platelet drop of greater than 50% from baseline and a new deep vein thrombosis 5 to 10 days after starting heparin therapy. HIT is a prothrombotic disorder caused by IgG autoantibodies targeting platelet factor 4 (PF4)-heparin complexes, leading to widespread platelet activation and consumption. The immediate standard of care for high clinical suspicion of HIT (indicated by a high 4T score) is to stop all heparin exposure immediately and initiate anticoagulation with a non-heparin agent, such as a direct thrombin inhibitor (e.g., argatroban, bivalirudin) or fondaparinux. This must be done empirically without waiting for confirmatory laboratory testing.

Adım Adım Çözüm

1
Calculate the 4T score based on the patient's presentation.
The patient has a high probability score due to a platelet fall >50%, timing of 5-10 days after heparin exposure, new thrombosis (DVT), and no other apparent cause.
To determine the clinical likelihood of Heparin-Induced Thrombocytopenia (HIT) Type 2.
2
Determine the immediate necessary intervention for suspected HIT Type 2.
All heparin products must be immediately discontinued without waiting for confirmatory laboratory testing.
HIT Type 2 is an antibody-mediated, highly prothrombotic state; continuing heparin risks severe thrombotic complications.
3
Select the appropriate alternative anticoagulation.
Initiate a non-heparin anticoagulant, such as argatroban (a direct thrombin inhibitor).
Patients with HIT require ongoing anticoagulation for the new thrombosis, but alternative classes must be used to avoid cross-reactivity and further clotting.

Anahtar Kavram

Heparin-Induced Thrombocytopenia (HIT) Type 2 Diagnosis and Management
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Konular

Hematology and Oncology

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