Nutcracker syndrome, also known as left renal vein entrapment syndrome, is primarily caused by the compression and narrowing of the left renal vein at the angle between the abdominal aorta and the superior mesenteric artery, leading to a series of clinical symptoms.The main manifestations include recurrent, episodic hematuria and orthostatic proteinuria.Generally, as individuals age, the accumulation of fat and connective tissue at the angle between the superior mesenteric artery and the abdominal aorta increases, or collateral circulation develops, which can improve the congestive state and alleviate symptoms.Nutcracker syndrome predominantly affects tall and slender adolescents.In male patients, it may induce varicocele on the left side, potentially affecting semen quality and, consequently, the patient's fertility.