Having occult blood in urine is not the same as having hematuria! Hematuria, which refers to an increase in red blood cells in the urine, means ≥3 red blood cells per high-powered field of view in centrifugally precipitated urine; while urinary occult blood means hemoglobin or myoglobin in the urine. Red blood cells and hemoglobin and myoglobin are not the same thing. There are many factors that affect urine occult blood and the results can be false positive or false negative! If vitamin C is used clinically, it will be excreted from the urine in large amounts, it neutralizes the oxides in the urine test paper and cannot produce oxygen, causing a false reaction. And when the urinary tract infection, certain bacteria can produce peroxidase, causing a false positive; some crystals can also affect the determination of occult blood, causing a false positive result; some trauma or tissue infection will make the urine contains myoglobin will also make the urine occult blood is positive. In addition, urine occult blood test is also subject to some external factors such as whether the specimen is fresh, whether the reaction time is appropriate, whether the test strips are expired or contaminated, etc., which can cause false positive or false negative results of urine occult blood test. The diagnosis of hematuria cannot be based on urine occult blood alone, but mainly on urine sediment microscopy. Therefore, parents should not be anxious when their child has positive urine occult blood, they need to look at the microscopic red blood cell count, do not think that the so-called “nephritis” because of positive urine occult blood and blindly seek medical advice and medication.