First, true and false hematuria: pediatric hematuria should first pay attention to identify true and false hematuria. Normal fresh urine is clear, colorless or yellowish liquid, with a trace of protein (not more than 30-100 mg per day), also contains a small number of red blood cells (not more than 1.5 million per day). Hematuria is the presence of more than the normal amount of red blood cells in the urine, which is a common symptom, often suggesting diseases of the urinary system (i.e., the kidney, ureter, bladder and urethra, etc.), and must be clinically analyzed to determine the cause of hematuria and provide the necessary treatment. Clinically, according to the degree of hematuria can be divided into two kinds of hematuria and microscopic hematuria. When 1 liter of urine contains more than 1 ml of blood, the urine is light red, visible to the naked eye, called hematuria. Of course, when the urine is acidic can also be strong tea color, sometimes with blood or blood clots, centrifuged red blood cell deposits, under the microscope urine sediment can be seen in a large number of red blood cells. If the naked eye is not bloody, in the microscope under the high power field of view of the centrifugal urine (test tube put 10 ml of urine, and then put into the centrifuge at 1800 revolutions per minute for 5 minutes, take out the bottom of the test tube to observe the urine sediment, that is, called centrifugal urine), if more than 5 erythrocytes, or not centrifuged urine more than 1 ~ 2, or collected for 12 hours of urine sediment (Edith’s count) more than 500,000 can be diagnosed as Microscopic hematuria is diagnosed. It is worth noting that the following cases are not true hematuria: (1) red urine: after taking certain foods, drugs, dye pigments, urine can be red, but there is no erythrocyte increase in the urine, the occult blood test is also negative. (2) hemoglobinuria: in a large number of hemolysis, or a part of the body can appear when a serious squeeze injury, the appearance of wine-like uniform transparent, centrifuged urine color remains unchanged, negative microscopic examination, but the occult blood test is positive. (3) the body metabolites caused by changes in urine color: such as porphyrinuria (seen in porphyria or lead poisoning), sun exposure can be red, red blood cells in the urine does not increase, negative occult blood, but the urine porphyrin test is positive. In addition, newborns in the first few days of life can have urate urine, diaper red, but the microscopic erythrocytes are not much and there are a lot of urate crystals. (4) Bleeding outside the urinary tract mixed into the urine: neighboring organs such as vaginal, perianal bleeding, gastrointestinal bleeding and other foreign blood mixed into the urine, will also form pseudohematuria, detailed physical examination and fresh urine specimens for review to clarify the diagnosis. Hematuria: Although hematuria is a common clinical symptom in pediatrics, it has many causes and is often not easy to distinguish. In terms of diseases of the urinary system itself, primary, secondary and hereditary nephritis are the most common causes of hematuria in children, especially streptococcal post-infection nephritis is the most common. Infection of the urinary system in addition to bacteria can also be caused by viruses, mycoplasma, mycobacteria and parasites, such as renal tuberculosis is often hematuria, and can be the first symptom. Kidney, bladder and urethra stones can cause hematuria, especially in boys with the most common lower urethra stones. Congenital malformation of the urinary system, trauma, tumors, vascular disease, etc. is also the cause of hematuria. In addition, taking certain drugs such as sulfonamides, salicylic acid, anethole, anti-inflammatory pain, streptomycin, cyclophosphamide, mercury, arsenic and so on can also lead to hematuria. In addition, some systemic diseases are also the cause of hematuria, such as blood diseases, rheumatic diseases, infectious diseases (epidemic hemorrhagic fever, infective endocarditis and sepsis, etc.), metabolic diseases and nutritional vitamin K, vitamin C deficiency, and so on, which will not be repeated here. There is also a kind of transient hematuria, after strenuous exercise or overexertion, after resting to eliminate fatigue that disappears, known as functional hematuria. In addition to hematuria, the above diseases are also accompanied by other manifestations, such as nephritis, edema, hypertension, urinary tract infections, urinary frequency and urgency, drug hematuria, drug history, traumatic hematuria, traumatic lumbar injuries, and so on, as long as the doctor carefully asked about the history and examination of the cause of the disease can be clear. Third, pediatric asymptomatic hematuria (also known as simple hematuria) is more common, the following situations: (1) Nutcracker phenomenon (also known as the left renal vein compression syndrome): usually the left renal vein will not be compressed, but in puberty, rapid growth in height, lumbar spine overstretched, the left renal vein is compressed, resulting in hemodynamic changes that can lead to hemorrhage in the left kidney. Due to the different degree of bleeding, there may be recurrent episodes of hematuria, or microscopic hematuria, sometimes accompanied by left-sided lumbar pain. The diagnosis can be made with the help of ultrasound to observe the compression and distal dilatation, and with the help of CT examination or angiography. There is no need to worry after a clear diagnosis, hematuria disappears with age, and the prognosis is good. (2) Benign familial hematuria: it can occur at any period of time in children, and both men and women can develop the disease, mostly manifested as asymptomatic microscopic hematuria, and some cases can be seen as microscopic hematuria after a cold or exercise, but there is no edema and high blood pressure, and the condition is generally stable, and the diagnosis is relatively simple, as long as the parents are asked to do some urine tests, and the diagnosis is considered if one of the parents has hematuria as well. If a kidney puncture biopsy is performed and the thinning of the basement membrane is seen by electron microscopy, the diagnosis will be more fully based. There is no specific treatment for this disease, the prognosis is good, but should avoid colds or too strenuous physical activities, can be followed up regularly. (3) Hypercalciuria: This is a condition in which the amount of calcium excreted in the urine is significantly higher than normal. The amount of calcium excreted in normal urine does not exceed 4 mg per kilogram of body weight per day. Hematuria is the most common manifestation of pediatric hypercalciuria, which is generally believed to be caused by calcium crystals causing damage to the urinary tract. Individual children may have frequent urination, urinary urgency, urinary pain, difficulty in urination, enuresis, recurrent urinary tract infections, abdominal discomfort, back pain and other symptoms. Rarely, the disease may affect bone growth and result in short stature. The treatment of this disease is to drink plenty of water, appropriate restriction of calcium and sodium intake, avoid eating fruit juice and chocolate containing too much oxalic acid and other foods, so as to avoid generating calcium oxalate crystals in the urine. Thiazide diuretics can also be given, or can be used to prevent excessive intestinal calcium absorption by ion exchange resin sodium cellulose phosphate. (4) IgA nephropathy: Children with respiratory tract infections or gastrointestinal tract infections often occur at the same time or within 1~2 days of the occurrence of hematuria, usually within a few days to quickly disappear, without edema, hypertension or other discomfort. Individual older children may complain of low back pain, or transient difficulty urinating. Hematuria may recur several times, the length of the interval varies, the urine test is normal or there is persistent microscopic hematuria in the interval between episodes, and renal function tests are usually normal. There is still no specific treatment for this disease, and its prognosis is generally good, especially for pediatric patients. A small number of children with gradual decline in renal function, finally developed into chronic renal insufficiency. Fourth, how to treat pediatric hematuria: pediatric hematuria is very common, especially after the current urine screening and enhanced urine testing. Parents have to overcome two extreme attitudes: one is excessive tension and fear. Some parents are concerned that chronic hematuria in the pediatric population will lead to anemia, when in fact not much blood will be lost as far as hematuria itself is concerned. As mentioned earlier, 1 liter of urine mixed with 1 ml of blood can already make the urine slightly red to the naked eye. Some parents worry that pediatric hematuria will lead to renal failure, but in fact only a very small number of diseases with hematuria as the main sign of progression to renal failure. Sometimes urine microscopy negative, but positive occult blood “+ ~ + + +” also often make parents worry too much. It is important to understand that the occult blood test is affected by a variety of factors and can be used as a screening test, but the diagnosis of hematuria is mainly dependent on microscopy. There are also parents who do not understand the concept of medical values, and equate the tens of thousands of changes in the 12-hour urine sediment count with the real-life concept of “10,000”, causing unnecessary worry and fear. On the contrary, another tendency is not to take it seriously. It is also wrong to think that pediatric hematuria is a common phenomenon or has been diagnosed as benign, then rest easy and do not pay attention to follow-up. Certain serious and timely treatment of diseases, such as tumors, renal tuberculosis, etc., early treatment can be cured, late treatment is difficult to cure or even loss of life. Stones, hyperuricemia, etc. are curable, and some diseases without specific treatment, such as certain nephritis, IgA nephropathy, etc., must be followed up for a long period of time to observe whether they have progressed or not. In addition to hematuria, we should also pay attention to the presence and degree of urinary protein, and whether the blood pressure is elevated, because these two symptoms are sometimes more significant to the prognosis of the disease than hematuria. There are also some benign, do not have to cure and no rule of law, such as familial benign hematuria, acute streptococcal infection nephritis recovery, nutcracker phenomenon, etc., must pay attention to prevention and treatment of infections (such as respiratory infections), do not abuse the drug (especially containing nephrotoxicity such as cinnabar, etc.). Children usually should not “make up” too much. In general, hematuria, especially in asymptomatic cases, does not require a break from school and can usually be used for general activities. Girls should pay attention to vulvar hygiene, boys should pay attention to penile foreskin hygiene, lesions should be treated early.