A 45-year-old man with biopsy-proven primary membranous nephropathy and proteinuria of 11 g/day develops acute left flank pain and a fall in urine output. Doppler ultrasound shows absent flow in the left renal vein. What is the underlying reason for this complication?
- A Antibody mediated thrombosis of renal venous endothelium by anti-PLA2R
- B Direct invasion of the renal vein by the nephrotic inflammatory process
- C Loss of antithrombin III and other anticoagulant proteins in urine plus increased hepatic synthesis of fibrinogen ✓
- D Hypertension induced medial hyperplasia of the renal vein wall
Correct answer: C. Loss of antithrombin III and other anticoagulant proteins in urine plus increased hepatic synthesis of fibrinogen
Explanation
Membranous nephropathy carries one of the highest risks of thromboembolic events among nephrotic syndromes. Urinary loss of antithrombin III, protein A and protein S, together with hepatic overproduction of fibrinogen and increased platelet reactivity from hypoalbuminemia driven hyperlipidemia, creates a hypercoagulable state. Renal vein thrombosis is the classic manifestation and may present with flank pain and worsening renal function. The other options describe mechanisms that do not operate here.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.