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Zorluk: OrtaHematology and Oncology

A 68-year-old man is evaluated in the hospital on postoperative day 6 following an elective right total hip arthroplasty. His postoperative course had been unremarkable until today, when he developed new-onset pain and swelling in his left calf. He has been receiving subcutaneous unfractionated heparin for deep vein thrombosis prophylaxis since the day of surgery. Temperature is 37.4∘C37.4^\circ\text{C} (99.3∘F99.3^\circ\text{F}), blood pressure is 134/82 mm Hg134/82\text{ mm Hg}, pulse is 92/min92/\text{min}, and respiratory rate is 16/min16/\text{min}. Physical examination reveals a swollen, tender left calf with mild erythema. Laboratory studies are obtained:

Laboratory TestResultReference Range
Hemoglobin13.5 g/dL13.5\text{ g/dL}13.5−17.5 g/dL13.5-17.5\text{ g/dL}
Leukocyte count8,200/mm38,200/\text{mm}^34,500−11,000/mm34,500-11,000/\text{mm}^3
Platelet count75,000/mm375,000/\text{mm}^3150,000−400,000/mm3150,000-400,000/\text{mm}^3

Review of his admission laboratory results from six days ago shows a platelet count of 230,000/mm3230,000/\text{mm}^3.

What is the most appropriate next step in management?

  1. A
    Switch unfractionated heparin to enoxaparin
  2. B
    Transfuse one unit of apheresis platelets
  3. Discontinue unfractionated heparin and initiate argatrobanCevap
  4. D
    Continue unfractionated heparin and order lower extremity venous ultrasonography
  5. E
    Obtain blood cultures and start broad-spectrum intravenous antibiotics

Cevap

Discontinue unfractionated heparin and initiate argatroban
The correct answer addresses a high clinical suspicion for Heparin-Induced Thrombocytopenia (HIT) type 2. HIT typically presents 5 to 10 days after starting heparin with a platelet count drop of >50%. Because it is a highly prothrombotic state (evidenced here by the likely new DVT), the immediate life-saving intervention is to discontinue all heparin products and initiate an alternative anticoagulant, such as a direct thrombin inhibitor (e.g., argatroban, bivalirudin) or fondaparinux.

Adım Adım Çözüm

1
Calculate the platelet count drop and assess the timeline of onset.
The platelet count dropped by greater than 50% (from 230,000 to 75,000) exactly 6 days after heparin initiation.
Applying the 4T criteria (Thrombocytopenia, Timing, Thrombosis, oTher causes) establishes a high pretest probability for Heparin-Induced Thrombocytopenia (HIT).
2
Evaluate the clinical presentation in the context of the laboratory findings.
The new-onset calf pain and swelling indicates a probable new deep vein thrombosis (DVT).
HIT is highly prothrombotic due to antibody-mediated platelet activation, frequently leading to new venous or arterial clots despite the low platelet count.
3
Determine the required acute intervention for highly suspected HIT.
Immediate cessation of unfractionated heparin and initiation of argatroban is selected.
Continuing any heparin product (including LMWH) fuels the antibody cascade. A non-heparin anticoagulant like a direct thrombin inhibitor must be started empirically before confirmatory labs result.

Anahtar Kavram

Diagnosis and management of Heparin-Induced Thrombocytopenia (HIT)
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Konular

Hematology and Oncology

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