Examkin

Question

Difficulty: MediumHemodynamic and Coagulation Processes

A 68-year-old woman is admitted to the hospital with a 2-day history of acute-onset right leg pain and swelling. She has a history of type 2 diabetes mellitus, hypertension, and advanced chronic kidney disease. Her current medications include amlodipine, lisinopril, and insulin glargine. Vital signs are temperature 37.1°C (98.8°F), blood pressure 142/86 mm Hg, heart rate 88/min, and respiratory rate 16/min. Physical examination reveals pitting edema, erythema, and tenderness of the right lower extremity extending to the mid-thigh. Laboratory studies show:

Serum creatinine: 4.8 mg/dL (Estimated glomerular filtration rate: 11 mL/min/1.73 m²)
Platelet count: 180,000/mm³
Prothrombin time: 11 seconds
Partial thromboplastin time: 28 seconds

Compression ultrasonography of the right lower extremity confirms a deep vein thrombosis in the right femoral vein. The decision is made to initiate immediate systemic anticoagulation. Which of the following is the most appropriate initial pharmacotherapy for this patient?

  1. A
    Subcutaneous enoxaparin
  2. B
    Oral rivaroxaban
  3. Intravenous unfractionated heparinAnswer
  4. D
    Subcutaneous fondaparinux
  5. E
    Oral warfarin

Answer

Intravenous unfractionated heparin
The correct answer is intravenous unfractionated heparin. This patient presents with an acute deep vein thrombosis and requires immediate systemic anticoagulation. A critical factor in selecting her therapy is her severe chronic kidney disease (eGFR 11 mL/min/1.73 m²). Unfractionated heparin is primarily metabolized by the reticuloendothelial system and macrophages. Its clearance is relatively unaffected by renal function, making it the safest and most appropriate initial choice for patients with an eGFR < 30 mL/min/1.73 m².

Step-by-Step Solution

1
Diagnose the acute condition requiring treatment.
The patient has an acute deep vein thrombosis (DVT) in the right femoral vein.
Compression ultrasonography confirmed the presence of the clot, establishing the need for immediate systemic anticoagulation.
2
Identify patient-specific modifiers that influence pharmacotherapy selection.
The patient has severe chronic kidney disease (CKD stage 5) with an eGFR of 11 mL/min/1.73 m².
Anticoagulants have varying degrees of renal clearance, and severe renal impairment significantly alters their safety profiles and contraindications.
3
Select the appropriate anticoagulant based on the patient's renal function.
Intravenous unfractionated heparin is selected as the initial therapy.
Unfractionated heparin is cleared by the reticuloendothelial system and does not pose an accumulation risk in severe renal failure, unlike low-molecular-weight heparins, fondaparinux, and most direct oral anticoagulants.

Key Concept

In patients with severe renal impairment (eGFR < 30 mL/min/1.73 m²), intravenous unfractionated heparin is the preferred initial anticoagulant for acute venous thromboembolism because it is primarily cleared by the reticuloendothelial system, avoiding the toxic drug accumulation seen with renally cleared agents.
Rate this question

Topics

Hemodynamic and Coagulation Processes

More questions from this topic