Urine test red blood cells 266/ul may be due to infection, stones, tumors and other reasons, whether serious need to be combined with the specific analysis of the condition. Urinalysis red blood cells 266/ul, suggesting hematuria, generally common in infections, stones, tumors and other diseases, but hematuria and the severity of the disease is not proportional to the severity of the seriousness of the disease, whether it is serious need to be combined with the symptoms, signs, other test results and other comprehensive assessment. 1. Infection: common urinary tract infections can lead to hematuria, such as cystitis, pyelonephritis and so on. If there is only back pain, urinary frequency, urinary urgency, urinary pain and other urinary symptoms, the general condition is not serious, but if there are fever, chills and other systemic symptoms, and even a drop in blood pressure and other manifestations of individual, indicating that the condition is more serious, there is a possibility of infectious shock. 2. Stones: Ureteral stones, kidney stones, etc. Due to mechanical stimulation, hematuria can occur. If the stones are small and do not cause hydronephrosis or infection, the condition is generally not serious. If the stones have caused obvious hydronephrosis or concurrent infection, the condition is generally more serious and even renal atrophy may occur. 3. Tumor: bladder cancer, renal pelvis cancer, etc., due to the rupture of blood vessels on the surface of tumor, hematuria may appear. If it is considered or diagnosed as tumor, it is usually more serious and needs to be treated as soon as possible. If abnormalities are found, further examination should be carried out to clarify the diagnosis, and regular treatment should be carried out according to the doctor’s opinion.