During a scheduled ambulatory clinic visit, a 57-year-old woman reports a 3-day history of… — USMLE Step 3

During a scheduled ambulatory clinic visit, a $57$ -year-old woman reports a $3$ -day history of escalating pain and swelling in her left lower extremity. Her medical history is significant for hypertension, diabetic nephropathy, and morbid obesity. Her current medications include nifedipine, sitagliptin, and subcutaneous insulin detemir. Blood pressure is $142/88$ mmHg, pulse is $82$ /min, and respirations are $16$ /min. Pulse oximetry shows $98\%$ on room air. Physical examination reveals that the left calf is erythematous, warm, and measures $5$ cm larger in circumference than the right calf. A compressive duplex ultrasonography reveals an acute, noncompressible thrombus in the left popliteal vein. Laboratory studies show:

Hemoglobin: $11.8$ g/dL
Platelet count: $230,000$ /mm $^3$
Serum creatinine: $3.1$ mg/dL
Estimated glomerular filtration rate (eGFR): $19$ mL/min/ $1.73$ m $^2$

The patient is hemodynamically stable with normal oxygenation. The physician determines she is an appropriate candidate for immediate outpatient management of her deep vein thrombosis.

Which of the following is the most appropriate pharmacologic intervention for this patient?

Oral apixabanAnswer
B
Subcutaneous enoxaparin
C
Oral rivaroxaban
D
Oral dabigatran
E
Intravenous unfractionated heparin

Answer

Oral apixaban is the correct choice because it is safe and approved for use in severe renal impairment and allows for outpatient treatment without routine monitoring.

Oral apixaban is the most appropriate pharmacologic intervention for this patient. She requires immediate anticoagulation for an acute deep vein thrombosis in an outpatient setting. However, her severe chronic kidney disease (eGFR

19

mL/min/

1.73

^2

) limits her therapeutic options. Apixaban is primarily metabolized by the liver and is FDA-approved and considered safe for patients with severe renal impairment (including end-stage renal disease on dialysis). It provides effective anticoagulation without the need for parenteral bridging or routine coagulation monitoring.

Step-by-Step Solution

Diagnose the acute condition and determine the appropriate treatment setting.

The patient has an acute left lower extremity deep vein thrombosis. Being hemodynamically stable, she is a candidate for outpatient anticoagulation.

Initial stabilization and triage guide the choice of inpatient versus outpatient pharmacologic regimens.

Evaluate patient-specific contraindications to standard therapies.

The patient has severe chronic kidney disease with an eGFR of

19

mL/min/

1.73

^2

Renal function strictly dictates the safety, dosing, and selection of various anticoagulant medications.

Select the optimal anticoagulant based on the renal profile and outpatient setting.

Oral apixaban is selected.

Apixaban undergoes minimal renal clearance compared to other direct oral anticoagulants and is safe in severe renal impairment (eGFR

< 25

mL/min/

1.73

^2

). It requires no injection bridging or laboratory monitoring.

Key Concept

Safe selection of oral anticoagulants in the setting of acute deep vein thrombosis and severe chronic kidney disease.

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