How to determine true hematuria and pseudohematuria in children with red urine? We all know that normal urine is light yellow, but when you find that your child has abnormal urine color, such as after the urine is soy sauce-colored urine or red urine, first do not panic, but first to distinguish whether it is true hematuria or pseudohematuria, that is, to exclude some conditions that make your child have a change in urine color but actually not hematuria. Some drugs such as aminopyrine, sodium phenytoin, rifampin and phenol red can cause red urine in children, or the pigments in certain foods and vegetables and uric acid salts produced by human metabolism can make the urine red, but this is not hematuria, and at this time a urine examination shows that the occult blood test and microscopy This is not hematuria, but a urinalysis can show negative occult blood test and microscopic examination of red blood cells, so hematuria can be excluded. (2) We need to pay attention to the change of urine color caused by hemoglobinuria and myoglobinuria, such as paroxysmal sleep hemoglobinuria, hemolytic anemia, etc. In this case, the urine can be soy sauce color or coffee color, which is caused by hemolysis of red blood cells after destruction of hemoglobinuria, at this time, the urine examination is positive for urine occult blood test, but the microscopic examination does not have red blood cells or occasional red blood cells. Myoglobinuria is an acute destruction of muscle tissue caused by various causes, resulting in rhabdomyolysis and myoglobin excretion from the urine, which can be accompanied by myalgia, muscle swelling, muscle weakness, etc. Myoglobinuria can be pink or dark brown in color. Urine myoglobin test is positive. Myoglobin is soluble in 80% saturated ammonium sulfate solution, while hemoglobinuria is insoluble. It is possible to distinguish between myoglobinuria and hemoglobinuria by this point. This is to help clinicians judge the condition and diagnose and treat correctly. (3) Non-urinary tract bleeding such as vaginal or lower gastrointestinal bleeding mixed into the urine, menstrual contamination of urine, etc. In this case, the urine occult blood test and microscopic examination of red blood cells are positive, but the blood in the urine is not the red blood cells of urinary tract origin. This requires detailed questioning and physical examination by the receiving physician to identify. Only after the above three conditions are ruled out can the child be diagnosed with true hematuria, which is what we usually call hematuria. In the context of the resources available in the community health center, what is the best diagnostic procedure for pediatric hematuria admissions in order to avoid excessive laboratory tests and to identify the fastest possible cause? What happens when pediatric hematuria is identified? When hematuria is detected in a child, parents are generally very nervous and anxious to identify the cause. The current diagnostic process is (1) to determine the source of the hematuria; at present, according to the morphological changes of red blood cells in the urine, hematuria is divided into two categories: glomerular and non-glomerular hematuria: glomerular hematuria refers to hematuria originating from the glomerulus, and the red blood cells in the urine appear in various sizes and morphological changes, i.e. deformed red blood cells. Red blood cells are predominant; if the microscopic red blood cells have a single morphology and resemble peripheral blood, it is homogeneous hematuria. This is because the hematuria originates from the urinary system below the renal unit and is due to the rupture and bleeding of the blood vessels in the urinary tract, so the morphology of the red blood cells in the urine is basically normal and homogeneous. Generally speaking, more than 95% of pediatric hematuria is due to diseases of the urinary system itself. The common causes of glomerular hematuria are: primary, secondary and hereditary glomerular diseases, such as acute nephritis, IgA nephropathy, nephrotic syndrome, lupus nephritis, purpura nephritis, hereditary nephritis, etc. Non-glomerular hematuria is common in: urinary tract infection, stones, tuberculosis, hypercalciuria, left renal vein compression or nutcracker phenomenon, congenital urinary tract malformation, drug-induced kidney and bladder injury, tumor, trauma, etc. In addition, it is also seen in systemic bleeding disorders, such as thrombocytopenic purpura, hemophilia, leukemia, malignant histiocytosis, aplastic anemia, etc. If a community health center hospital is not able to perform morphological testing of urine red blood cells, the following methods are also available. (2) The urine three cups test can be used to locate and analyze hematuria: ① Primary hematuria: It is only seen at the beginning of urination and the lesion is mostly in the urethra. Generally, it is mostly urinary infection and urethral disease. (2) Terminal hematuria: hematuria occurs at the end of urination, and the lesions are mostly in the bladder triangle, bladder neck or posterior urethra, and cystitis is common. ③Total hematuria: It means that hematuria appears in the whole process of urination, and the bleeding site is mostly in the bladder, ureter or kidney. If the hematuria is “total hematuria” and the blood is dark red, it is usually caused by diseases of the kidneys. The identification of the above three types of hematuria is the basis for proper treatment. (3) Laboratory tests: Elevated blood leukocytes are an important clue to the diagnosis of infectious diseases: scarlet fever, urinary tract infections such as acute and chronic pyelonephritis, acute cystitis, urethritis, urinary tuberculosis, urinary fungal infections and so on. Hematuria with more severe proteinuria is almost always a symptom of glomerular hematuria. High urinary calcium is an important clue that hematuria is caused by hypercalciuria. Tubular patterns in the urine sediment, especially red blood cells, indicate bleeding from the renal parenchyma and are mainly seen in glomerulonephritis. Ultrasound of the urinary system is used to diagnose nutcracker phenomenon (the disease is caused by compression of the left renal vein that travels between the abdominal aorta and the superior mesenteric artery, causing a persistent hematuria called nutcracker phenomenon. Normally, the right renal vein injects directly into the inferior vena cava, while the left renal vein needs to cross the angle formed by the abdominal aorta and superior mesenteric artery to inject into the inferior vena cava. Normally, this angle is 45°-60°, but if it is congenitally too small or filled with mesenteric fat, enlarged lymph nodes or peritoneum, it can cause the nutcracker phenomenon. (Diagnosis mainly relies on ultrasound, CT or renal venography) and congenital anomalies such as congenital polycystic kidney are important tools, and blood system examination is an important basis for excluding systemic bleeding disorders. (4) Clinical manifestations The diagnosis of hereditary nephritis is based on a combination of age, medical history, accompanying symptoms and signs, and laboratory tests. Hematuria with edema and hypertension is mostly seen in glomerulonephritis; hematuria with renal colic is seen in urinary stones; hematuria with pus and bladder irritation is seen in urinary tract infection; hematuria with renal mass is seen in tumor or polycystic kidney; hematuria with skin and mucous membrane bleeding is seen in hematological disease, infectious disease and other systemic diseases; hematuria with celiac disease is seen in filariasis. (4) If the diagnosis is still not clear according to the above procedures, a kidney biopsy can be done with parental consent if necessary to confirm the diagnosis. In conclusion, hematuria is a complex problem with multiple etiologies, and early examination and diagnosis can be made after the discovery of hematuria in order to obtain timely treatment. For simple microscopic hematuria, which is difficult to be diagnosed at the moment, we can follow up for a long time and go to the hospital for regular review and dynamic observation until the final diagnosis is clear.