A 40-year-old man with biopsy-proven primary membranous nephropathy presents with sudden left flank pain and a fall in urine output. Doppler ultrasound shows absent flow in the left renal vein. Which feature of his nephrotic syndrome most directly explains this complication?
- A Hypercholesterolaemia
- B Hypoalbuminaemia
- C Urinary loss of antithrombin III ✓
- D Sodium retention
Correct answer: C. Urinary loss of antithrombin III
Explanation
Renal vein thrombosis is the classic thrombotic complication of membranous nephropathy. Loss of antithrombin III (along with protein B and protein S) in urine creates a hypercoagulable state; loss of plasminogen also impairs fibrinolysis. Hypoalbuminaemia drives oedema via reduced oncotic pressure and hepatic lipoprotein synthesis causes hypercholesterolaemia, but neither is the prothrombotic mechanism. Membranous nephropathy carries the highest risk of renal vein thrombosis among glomerular diseases.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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