There are more reasons for hematuria in boys, which may be due to physiological and pathological reasons, such as ureteral stones, kidney tumors and so on. 1. Physiological reasons: some drugs such as metronidazole tablets, after taking the drug will appear dark red urine, this urine is not hematuria, just similar color, usually stop the drug within a few days will be restored. 2. Pathologic causes: (1) Ureteral stone: when the stone reaches the ureter with urine, the larger stone may get stuck and damage the mucosal blood vessels, which leads to bleeding and causes hematuria. (2) Kidney tumor: the tumor may continue to develop, and when it invades the blood vessels of the surrounding tissues, rupture occurs to produce hematuria, which is often manifested as painless hematuria of the naked eye. Abnormal urine color or hematuria may also be caused by other factors, it is recommended that patients go to regular hospitals in time, follow the doctor’s instructions for further examination, with the help of the doctor to clarify the cause, and targeted treatment or therapy.