1, hematuria is defined as more than normal amount of red blood cells in urine. Take 10ML of clean fresh middle urine, centrifuge 1500 rpm for 5 minutes, and microscopic examination of the sediment with 3 red blood cells/high magnification field is only when hematuria. Therefore, hematuria cannot be diagnosed by positive urine occult blood alone. 2, when the child has hematuria, we must first determine whether it is real or pseudo. Pseudohematuria can be seen in: Yang Yan, Department of Traditional Chinese Medicine, Beijing Children’s Hospital (1) Red urine: certain metabolites in the urine such as porphyrinuria, urea black acid urine (tyrosine metabolism abnormal disease) and drugs such as phenol red, aminopyrine, rifampin, etc. can make the urine red. Newborns can also have red urine when more uric acid is excreted in the urine, and the pigments in certain foods can also cause red urine. In this case, the urine occult blood test and microscopic examination of red blood cells are negative. (2) Hemoglobinuria and myoglobinuria: such as paroxysmal sleep hemoglobinuria and hemolytic anemia. In this case, urine occult blood is positive, but microscopic examination of red blood cells is negative. (3) Non-urinary tract bleeding: such as vaginal or lower gastrointestinal bleeding mixed in, menstrual contamination, etc. At this time, attention should be paid to differentiation. When the diagnosis of allergic purpura is clear, accompanied by positive urine protein, or microscopic examination of 3 red blood cells/HP, and the urine routine is abnormal for 2 times in 1 week or 3 times in 2 weeks, and other causes of hematuria are excluded, the clinical diagnosis of allergic purpura nephritis can be made, and if necessary, a kidney biopsy is also needed to clarify. Therefore, a positive urine occult blood alone cannot be diagnosed as allergic purpura nephritis.