Parents get anxious once their child develops hematuria. In fact, there are many causes of hematuria in children, representing the different health conditions of the child, so parents can observe carefully and not panic. If the child has glomerular hematuria once, it is important to identify the cause so that the specific condition can be understood for early and symptomatic treatment. What are the specific causes of hematuria in children: 1. Pediatric glomerular hematuria: ① Nephrotic syndrome: hematuria with edema, massive proteinuria, hypercholesterolemia and hypoproteinemia on blood chemistry. ② Glomerulonephritis: Children with this disease often have a recent history of skin growth, pustules, boils or pharyngitis, tonsillitis, etc., accompanied by hematuria with oliguria, swelling, and hypertension. Urine tests may show red blood cells, protein, and tubularity. (③) Lupus nephritis: Most often seen in children over 7 years of age, with more incidences in girls and occasionally in infants and children under 3 years of age. In addition to hematuria, there may be high or low fever and a bright red skin rash, typically butterfly-shaped, as well as maculopapular rash, erythematous rash, and maculopapular rash. Most pediatric patients have joint pain, cardiomyopathic changes, and also lesions in the lungs, gastrointestinal tract, blood, nerves, and many other systems. ④ Purpura nephritis: In addition to hematuria, the affected children may also have abdominal pain, joint swelling, and a hemorrhagic skin rash that appears densely around both lower limbs or ankles, followed by the buttocks and upper limbs. This rash is initially a pink papule, later the color deepens to form an erythematous spot, the center of the erythematous spot occurs punctate hemorrhage, the color turns dark purple. ⑤ Epidemic hemorrhagic fever: The disease initially presents with fever, flushing of the face, neck, and upper chest, and hypotension, hydronephrosis, hematuria, and shock after the fever subsides. ⑥ Pulmonary hemorrhagic nephritis syndrome: hematuria with unexplained fever, wasting, anemia, and hemoptysis. (7) Hereditary nephritis: manifests as persistent or recurrent microscopic hematuria or carnivorous hematuria. The condition worsens after acute respiratory infections, and about 30% to 40% of children have exacerbations. About 30% to 40% of children have neurological deafness and about 20% have ophthalmopathy, and renal failure develops in adulthood. Families often have patients with deafness, ophthalmopathy and renal failure. 2, pediatric drug hematuria: Some drugs are nephrotoxic, such as gentamicin, kanamycin, streptomycin, etc. can cause hematuria; some drugs, such as pautaxone, polymyxin, sulfonamides, etc. cause interstitial nephritis through the immune mechanism, manifested as hematuria, urine, low back pain, abdominal pain, rash, etc. For this reason, it is best to go to the hospital as soon as possible when hematuria occurs in children to avoid misdiagnosis. 3.Pediatric non-glomerular hematuria: ①Congenital malformations such as polycystic kidney and pelvic effusion can also cause hematuria. If hematuria is accompanied by abnormal urination such as frequent urination, urgent urination and painful urination, urinary tract infection, renal tuberculosis, hemorrhagic cystitis and urethral foreign body should be considered; if hematuria is accompanied by back pain or abdominal pain, it may be urethral stone. If hematuria is accompanied by generalized bleeding, consider blood disorders such as thrombocytopenia and hemophilia; some vitamin (such as vitamin K1 and vitamin C) deficiencies can also appear in hematuria. ③ Idiopathic hypercalciuria: In addition to hematuria, there are no other symptoms, and laboratory tests can reveal increased urinary calcium excretion, and the incidence of kidney stones in families is as high as 30% to 70%. ④Nutcracker phenomenon, also called left renal vein compression syndrome, which means hematuria or proteinuria occurs after the vein is compressed. ⑤ Urological tumor: common in children is renal embryoma, which does not appear in the early stage of the disease, but when it appears, most children with the disease can feel the mass in the abdomen, and the mass can be found during ultrasound and CT examination. In addition, children with hematuria should be asked if they have eaten or taken any food or medicine that can cause hematuria, or if they have had a cold or tonsillitis before the hematuria. If a child is tested for hematuria, the parents also need to have a urine test, and if one parent has an abnormality, the siblings of the abnormal parent need to be tested to find out if the hematuria is familial. Familial benign recurrent hematuria usually has a good outcome, and there is no need to worry too much about it.