In the nephrology clinic, we often see many patients who visit the clinic for hematuria. Many of them are worried about the appearance of hematuria, and they even go from one hospital to another and take various kinds of medications to treat it. However, is this necessary and how should we look at hematuria? Today, we will introduce you to the knowledge about hematuria. First of all, red urine is not equal to hematuria, and many red foods and medications can also cause red urine. Clinically, a microscopic examination of urine sediment after centrifugation with more than 3 red cells per high-powered field of view or a flow-through count of urine red cells above the normal value of laboratory tests is defined as hematuria. Positive urine occult blood is not necessarily hematuria. Generally speaking, hematuria is divided into 2 categories: one is hematuria caused by various nephritis, which is called medical hematuria; the other is hematuria caused by bleeding in the urinary system (including kidney, ureter, bladder or urinary tract) due to various reasons, which is called surgical hematuria. The presence of medical hematuria indicates the presence of some kind of primary or secondary glomerulonephritis, while surgical hematuria is caused by a wide variety of diseases, with common causes including urinary tract infections, stones, tumors, etc. Does hematuria need to be treated? The source and cause of hematuria should be determined first. If there are blood clots or blood streaks in the urine or if the hematuria appears only at a certain stage of the urination process, it suggests that the hematuria is caused by a surgical disease, and we recommend that you promptly visit the urology department for appropriate consultation and treatment. Especially in elderly people, you should be alert to the occurrence of urological tumors. If hematuria is accompanied by symptoms of urinary frequency, urinary urgency and urinary pain, it usually indicates that the hematuria is related to urinary tract infection, and you are advised to visit a hospital promptly and receive standardized anti-infection treatment. In case of hematuria without conscious symptoms, whether it is visible to the naked eye or detected by urinalysis, it is recommended that you visit a nephrologist for further examination to clarify the cause. In the Department of Nephrology, we recommend that you have a urine red blood cell panel and a urinary ultrasound to distinguish between medical and surgical hematuria, and that you have a detailed history and symptoms to help identify the cause of the hematuria. For patients with hematuria that requires aggressive treatment, the doctor will give you appropriate treatment recommendations. For children and adolescents with hematuria, a renal vein ultrasound may be recommended to rule out left renal vein compression syndrome (“Nutcracker” phenomenon). Generally speaking, most asymptomatic medical hematuria, in the absence of secondary disease, is considered to be a benign primary glomerulonephritis, and most patients do not experience further kidney damage as a result. At the same time, you are advised to avoid various factors that may cause or aggravate kidney damage in your life, including trying to prevent infections, avoiding overexertion, and especially avoiding the use of drugs that have kidney damage. However, once infection occurs, you should also avoid the application of nephrotoxic drugs during active treatment therapy in a timely manner.