Nutcracker syndrome (NCS) is defined as the presence of signs and symptoms accompanying compression of the left renal vein. Although it is often a benign condition, it is rare in childhood, and data on treatment and follow-up are limited. This study aimed to examine the clinical and laboratory findings at the presentation and follow-up of pediatric NCS patients and obtain information about prognosis. Medical records of pediatric patients diagnosed with NCS between January 2017 and August 2024 were retrospectively investigated. Demographic, clinical, and laboratory findings of the patients at diagnosis and follow-up were recorded. The study included 31 patients (23 females, 8 males) diagnosed with NCS, with a mean age at diagnosis of 11.7 ± 3.6 years. Twenty-eight (90.3%) patients were asymptomatic. The most common presentation [22 patients (71%)] was isolated proteinuria. Twenty-seven (87%) patients were followed for a median of 17 (1.6-97.4) months. Complete clinical and laboratory recovery was observed in 10 (37%) patients. Eight (29.6%) patients had isolated microalbuminuria at the last visit. A significant decrease in proteinuria and increased body mass index (BMI) z-score were detected during the follow-up period. All patients were followed up conservatively. No increase in symptoms, decrease in glomerular filtration rate, or increase in proteinuria was observed in any patient during the follow-up. NCS often presents with hematuria and/or proteinuria and should be excluded before invasive examinations such as kidney biopsy. Usually, it has a good course; conservative follow-up is sufficient in most patients, and the rate of improvement is high in parallel with the increase in BMI.

Keywords: Nutcracker syndrome, proteinuria, hematuria, postural proteinuria