Abstract: PUB319
When Occam's Razor Does Not Apply: Gross Hematuria in the Setting of Nutcracker Syndrome and Alport Syndrome
Session Information
Category: Pediatric Nephrology
- 1900 Pediatric Nephrology
Authors
- Khuvis, Joshua, University of Connecticut School of Medicine, Farmington, Connecticut, United States
- Zitnik, Edward M., University of Connecticut School of Medicine, Farmington, Connecticut, United States
Introduction
Nutcracker syndrome occurs due to left renal vein entrapment between the aorta and superior mesenteric artery, leading to venous congestion and collateral vessel formation. It is an uncommon but important cause of hematuria which often goes underdiagnosed given its variable presentation and difficulty to assess on ultrasound. Alport Syndrome occurs due to malformation of the type 4 collagen which makes up the glomerular basement membrane. It is classically X-linked but autosomal variants exist and can also cause hematuria. It is a known cause of progressive CKD and hematuria in children.
Case Description
The patient is a 12-year-old male with persistent painless hematuria for 4 months. At onset, he reported dark urine and had a positive rapid Strep swab. Labs were notable for positive ASO, but negative ANA with normal C3 and C4. Weeks after completing antibiotics, he continued to have pink-tinged urine and >60 dysmorphic RBC/hpf on microscopy. Family history was notable for father with recurrent gross hematuria in childhood attributed to trauma related to excessive biking, and a paternal grandmother with CKD of unknown cause. A renal ultrasound with doppler revealed narrowing of the aorto-mesenteric distance and the traversing segment of the left renal vein, consistent with Nutcracker syndrome. Genetic testing was performed due to the family history, persistent hematuria, and elevated blood pressure, revealing a heterozygous autosomal mutation in COL4A4.
Discussion
This case demonstrates a clinical scenario in which two rare causes of hematuria were identified in a single patient. Though the initial presentation was more consistent with post-infectious glomerulonephritis, a more common cause of painless hematuria in children, the recurrence of gross hematuria, and persistence of microscopic hematuria prompted further evaluation. It is uncertain how much the COL4A4 mutation contributes to his hematuria given the variable penetrance of autosomal mutations in Alport Syndrome, but the family history suggests the mutation may be pathologic. With expertise of our pediatric radiology team, we were able to make the diagnosis with doppler ultrasound using a specialized protocol and avoid unnecessary radiation from CT imaging. This case highlights the importance of anchoring bias, particularly in children with abnormal presentations of seemingly common conditions.