I. What is called hematuria When the red blood cell count in the urine exceeds the standard, it is called hematuria. When the number of red blood cells per high-powered field of view is greater than 3 or more on microscopic examination of the urine sediment after centrifugation, it is called hematuria. Hematuria may be reported in severe cases, or with a full field of view. There are several ways to classify hematuria. According to the degree of hematuria, it is divided into carnal hematuria and microscopic hematuria. The former is often flesh-washing or dark red in color and is often detected by the patient’s naked eye; the latter is often not significantly different from the usual urine color and requires the aid of a microscope to determine. According to the presence or absence of obvious clinical manifestations, hematuria can be further divided into symptomatic hematuria and asymptomatic hematuria. Symptomatic hematuria refers to patients with other urological symptoms in addition to hematuria, such as edema, urinary frequency, urinary urgency, urinary pain, back or abdominal pain, as well as hypertension, proteinuria, and renal hypofunction. Asymptomatic hematuria, on the other hand, is a condition in which the patient has no obvious symptoms other than hematuria and is not accompanied by the above conditions. The most meaningful classification of hematuria is based on the source of urinary red blood cells into glomerular and non-glomerular hematuria. Urine erythrocyte bitemporal examination is meaningful in distinguishing the source of urinary red blood cells. If the hematuria is of glomerular origin, the urine red blood cells are predominantly polymorphic on urine erythrocyte microscopy; conversely, they are predominantly homogeneous. In addition, glomerular hematuria may be characterized by varying degrees of proteinuria, or with erythrocyte tubularity, hypertension or renal insufficiency. Second, which conditions can lead to hematuria Many clinical conditions can lead to hematuria. Glomerular hematuria can be seen in: acute and chronic glomerulonephritis, purpura nephritis, hereditary nephritis, benign familial hematuria (thin basement membrane nephropathy), IgA nephropathy, thylakoid proliferative nephritis, etc. The common causes of non-glomerular hematuria include urinary malformation, renal calculi, idiopathic hypercalciuria, left renal vein compression syndrome, pharmacological hematuria, and exercise hematuria. Regardless of the presence or absence of symptoms, the cause of hematuria should be identified as far as possible. In addition to urinary red blood cell count and urine protein quantification, ultrasound examination of the urinary tract is also necessary to help detect malformations, stones, tumors, blood clots and surrounding tissues of the urinary system. In asymptomatic hematuria, if the hematuria originates from the glomerulus, a renal puncture biopsy is often required to make a definite diagnosis. Renal puncture biopsy can be considered if the following conditions are met: 1. The diagnostic criteria for glomerular hematuria are met by microscopic examination of red blood cells on urine sediment. 2. Asymptomatic hematuria has been present continuously or intermittently for more than 6 months. 3.Family history. 4, Urine protein quantification >0.2g/24H, qualitative (+). It is very important to follow up and review regularly to watch out for proteinuria, hypertension and renal impairment.