The normal range of red blood cells in urinalysis is within three per high-powered view, and if there are more than three per high-powered view, it is abnormal. Clinically mentioned hematuria generally includes two kinds: the first, is the naked eye hematuria, that is, looking at the urine appears red, the lightest color like the color of meat wash, and more concentrated. The second, microscopic hematuria, is when the color of the urine is normal, but during the urinalysis it is found that there are more red cells in the urine, more than three per high-powered field of view. But either way, both of these are called hematuria. There are many causes of hematuria, including renal causes, such as chronic nephritis, acute nephritis, purpura nephritis, lupus nephritis, etc.; there are also non-nephritic diseases of the urinary system, such as urinary stones, urinary tract infections, urinary tract tumors, etc.; there are also hematuria caused by diseases around the urinary system, such as appendicitis, pelvic inflammatory disease, rectal cancer. In addition, diseases of the blood system can also affect the urinary system and cause hematuria, such as thrombotic thrombocytopenic purpura and hemophilia. These diseases can affect platelets and clotting factors, which simply means that they affect the clotting system and can cause not only hematuria, but also bleeding in other areas.