Dual Origin of Hematuria in Concomitant Lupus Nephritis and Nutcracker Syndrome: A Case Report

Abstract

Background: Systemic lupus erythematosus is a multisystem autoimmune disease where lupus nephritis is a major cause of morbidity. Nutcracker syndrome, a rare vascular condition caused by left renal vein compression, presents with similar urinary findings. The coexistence of both is exceptional and creates a significant diagnostic challenge.  

Case Presentation: A 17-year-old female diagnosed with active Systemic lupus erythematosus and renal involvement, including proteinuria and microscopic hematuria.

Investigations: Initial investigations revealed proteinuria (1.19 g/24h) and significant microscopic hematuria (84 RBCs/HPF). While renal biopsy confirmed class III-A focal proliferative lupus nephritis, persistent postprandial abdominal pain led to an abdominal computed tomography scan, which demonstrated narrowing of the left renal vein between the aorta and superior mesenteric artery, consistent with anterior Nutcracker syndrome.

Treatment: The patient received pulse methylprednisolone, oral corticosteroids, hydroxychloroquine, and mycophenolate mofetil.

Outcome and Follow-up: After six months, Systemic lupus erythematosus activity significantly decreased (SELENA-SLEDAI score from 15 to 4) and proteinuria resolved completely. However, while abdominal pain resolved, microscopic hematuria persisted (24 RBCs/HPF) despite immunosuppressive therapy.

Conclusion: This case illustrates a dual mechanism of hematuria, involving lupus nephritis associated with the mechanical effect of Nutcracker syndrome. Recognizing Nutcracker syndrome as an independent cause of persistent hematuria in treated lupus nephritis is essential to prevent unnecessary escalation of immunosuppressive therapy.