Orthostatic Proteinuria without Left Renal Vein Entrapment in an Old Obese Female：A Case Report and Literature Review

Abstract Background Left renal vein (LRV) entrapment, namely nutcracker syndrome (NCS), is one of the most common causes of orthostatic proteinuria. In stereotype, orthostatic proteinuria is often accompanied by left renal vein obstruction and found in young and underweight individuals. Here, we report a rare case with orthostatic proteinuria in an old obese female caused by a type of rare congenital inferior vena cava (IVC) interruption. Case presentation This paper reported a 65-year-old obese woman, who suffered from fluctuated proteinuria, had been misdiagnosed as chronic glomerulitis for 30 years. Instead of having any sign of NCS, she had a unique type of IVC interruption. Most venous blood from infrarenal IVC and right kidney drained into her LRV, and then through the expanded communicating vessel, drained into the left ascending lumbar vein which extended as hemizygous vein. To the best of our knowledge, this is the first case of orthostatic proteinuria attributed to the subsequent hemodynamic irregularity caused by IVC interruption without LRV entrapment. Conclusion Adult-onset orthostatic proteinuria is relatively rare, hard to be recognized and could be misdiagnosed as chronic glomerulonephritis. The case provided a novel differential diagnostic condition for those who suffered from fluctuated proteinuria of unknown causes.