Nutcracker phenomenon, also known as left renal vein compression syndrome, is seen in children aged 13-16 years, especially in children with a relatively small and tall stature. It is a clinical condition caused by compression of the left renal vein on its journey into the inferior vena cava, due to the angle between the abdominal aorta and the superior mesenteric artery. The hematuria or proteinuria that can be produced clinically is usually upright hematuria or proteinuria, i.e., hematuria or proteinuria appears when the body is upright and disappears in a lying position, and is most often seen in the thinner and taller adolescent. The hematuria is of non-glomerular origin, but a small number of patients can present with glomerular origin hematuria and can be combined with upright proteinuria. Many experts believe that it is less likely to produce both hematuria and proteinuria. Patients have a good prognosis, and most will gradually improve in adulthood. Some children may also develop cribriform pain due to stasis in the testicular or ovarian veins, and men may also develop varicocele. Ren Xianqing, Department of Pediatrics, The First Affiliated Hospital of Henan College of Traditional Chinese Medicine Clinically, the diagnosis is often made with the help of ultrasound, and the diagnostic criteria are: the proximal internal diameter of the dilated part of the left renal vein before stenosis is more than 2 times wider than the internal diameter of the stenosis in the supine position, and the internal diameter of the dilated part is more than 4 times wider than the internal diameter of the stenosis after 15-20 minutes in the posterior spinal extension position (after uprightness), which can be diagnosed by taking two positions. There are also some units that have the above performance in addition to the diagnosis, plus the left renal vein dilated proximal blood flow velocity ≤ 0.09m/s after 15-20 minutes in the posterior spinal extension position, and the superior mesenteric artery and abdominal aorta angle within 9 degrees as the reference value. In children with asymptomatic hematuria and upright proteinuria caused by the nutcracker phenomenon, no specific treatment is needed, only follow-up. Generally, as the child grows older, the increase in fat and connective tissue at the angle between the superior mesenteric artery and the abdominal aorta or the establishment of collateral circulation improves the stasis status and the symptoms are relieved. Only a few children who present with persistent hematuria with pain require left renal vein shunts. In some adult patients with severe persistent recurrent hematuria, painful bleeding, and varicocele, surgery is considered only when conservative treatment is ineffective.