Nutcracker syndrome in pediatrics: initial findings and long-term follow-up results.

Background: Nutcracker syndrome (NCS) describes a set of symptoms and signs resulting from compression of the left renal vein (LRV). There is a lack of knowledge about its natural course, diagnosis, and management, especially in children. Herein, we present our single-center experience with a large number of patients who have long-term follow-up results.
Methods: All patients with NCS diagnosed between January 2011 and March 2021 were included and their data were obtained retrospectively.
Results: A total of 123 NCS patients (85 females) were included. The median age at the time of diagnosis was 12 (IQR 10-14) years, and BMI percentiles were below 5% in 38% of the cases. At the time of diagnosis, two-thirds of the patients were asymptomatic. The most common laboratory finding was nephritic proteinuria (98%), followed by microscopic hematuria (16%). Signs of LRV compression were significantly more evident in upright position Doppler ultrasonography (DUS) examination. All patients have been followed conservatively; hematuria and/or proteinuria resolved in 43 of the 108 patients (40%) within 35.8 ± 25.8 months of follow-up. Control DUS was performed in 52 patients after a mean period of 39.1 ± 21.3 months. The median peak velocity and diameter ratios of the LRV in the upright position were found to be decreased significantly when compared to the initial assessment (p < 0.05). Normal DUS findings were noted in 13 patients at the final evaluation.
Conclusions: In unexplained proteinuria and/or hematuria, NCS should be considered, especially in asthenic adolescents. Our results support conservative management in children as the first-line treatment approach.
(© 2023. The Author(s), under exclusive licence to International Pediatric Nephrology Association.)