Urine occult blood 0.3(+-)mg/l usually refers to weakly positive urine occult blood, suggesting that there are a small number of red blood cells in the urine, which may be caused by physiological reasons such as strenuous exercise, etc., and may also be caused by pathological reasons such as urinary tract infections, stones and other diseases. There are no red blood cells in normal urine, i.e. urine occult blood is negative. If the urine occult blood is weakly positive, you need to observe the number of red blood cells under the microscope, if the number of red blood cells per high magnification is less than three, it may not be true hematuria, or it may be caused by test errors. If the number of red blood cells is greater than three, belonging to the real hematuria, the more common causes are physiological and pathological. Physiologic causes are common in cases of strenuous exercise, fever, and left renal vein compression, but this is only transient and does not require special treatment. Pathological causes are more common in urinary tract infections, stones, tumors and various nephritis. If the patient has urine occult blood +-, it is recommended to go to the regular hospital in time, complete the examination to clarify the cause of the disease, under the guidance of the doctor to the targeted treatment or treatment.