A 58-year-old man comes to the emergency department complaining of severe pain in the right leg. He returned from Hawaii last night. The pain started mid flight without any notice. The patient has a history of IgA nephropathy and chronic kidney disease. His vital signs are given below: Height 6 ‘2; weight 342 lb; temperature is 98.4 ⁰ F, heart rate is 62 beats per minute, respiratory rate is 17 breaths per minute, and blood pressure is 145/88 mm Hg. Physical examination is significant for some tenderness over the right lower leg. Laboratory tests reveal the following: Test Result Reference range Erythrocyte count (RBC) 4.9 million/mm³ Male: 4.3 – 5.9 million/mm³ Female: 3.5 – 5.5 million/mm³ Erythrocyte sedimentation rate (Westergren) Male: 8 mm/h Male: 0-15 mm/h Female:0-20 mm/h Hematocrit 47% Male:41% – 53% Female: 36% – 46% Hemoglobin, blood 13.7 g/dL Male:13.5-17.5 g/dL Female 12.0 – 16.0 g/dL Creatinine 4.8 mg/dL 0.6 – 1.2 mg/dL Urea nitrogen 44 mg/dL 7-18 mg/dL Creatinine clearance 27 ml/min Male: 97 – 137 mL/min Female: 88 – 128 mL/min Sodium (Na⁺) 140 mEq/L 136 – 146 mEq/L Potassium (K⁺) 3.8 mEq/L 3.5 – 5.0 mEq/L Chloride (Cl⁻) 99 mEq/L 95 – 105 mEq/L Bicarbonate (HCO₃⁻) 26 mEq/L 22 – 28 mEq/L A duplex ultrasound of the right lower extremity shows a deep venous thrombosis. What is the most appropriate next step in the management of this patient?
