Hematuria is a common reason for patients to visit the urologist. We often encounter patients in the clinic with test sheets from multiple hospitals, hoping that the doctor will give a clear answer within three to five minutes, but they are often disappointed. Like “fever,” the causes of which can be written in a thick book; hematuria is just a symptom, and there are many different diseases that cause hematuria, and the treatment methods are very different. To get to the root of the problem, it takes a lot of effort to find the root cause. There are many causes, it is easy to confuse, and it is difficult to rush. Patients are often nervous when they see red urine, so what kind of thought process do doctors usually have when they see a patient with “hematuria”? 1. Is there really blood in the urine? Some patients say they have blood in their urine, or they see red blood cells in the test report, but it is an error in the test. For example, female patients can contaminate the urine specimen during menstruation; or the appearance of urine is red due to some drugs or food, once a friend’s child loved to eat red dragon fruit, and later found that the color of urine became pink, the result was a false alarm, it turned out to be the metabolism of red pigment inside the pulp disguised as “blood urine”. It turned out to be the metabolism of the red pigment inside the pulp disguised as “hematuria”. 2.Is there any pain when urinating blood? First of all, remember that painless hematuria requires a high degree of suspicion of urological tumors, especially in middle-aged and elderly people. Even if it occurs once, you should be highly alert and never come to the hospital because it is “better” and miss the best time for diagnosis and treatment. For example, urinary tract infections usually have pain in the abdomen, lower back pain or pain during urination, while patients with stones will have hematuria along with severe pain in the lower back. 3.What is the age and gender of the patient? The common causes of hematuria are different for patients of different ages. For example, in children or adolescents, if there is visual or microscopic hematuria, we should consider the possibility of nephropathy or congenital renal vascular malformation, and then physiological; for example, in young girls, urinary tract infection is relatively more common; while in middle-aged and elderly patients, we should first consider whether it is a urinary tract tumor, and only after ruling it out can we think about other aspects. 4.Is it medical or surgical hematuria? If your doctor gives you a test for “urine red blood cell count” or “red blood cell count”, it means that he wants to further identify whether the source of the hematuria is renal or post-renal. Simply put, if the red blood cells in the urine are present at the same time as the urine is produced, the red blood cells are compressed and deformed; if they are mixed in during transport after the urine is formed, the red blood cells are regular in form. Therefore, if deformed red blood cells are in the majority in the urine test, it is time to ask a nephrologist to take over further treatment. Internal hematuria also often has urine protein or tubular shape, and in appearance, the urine often shows a lot of foam. 5.Are there any other diseases? Some diseases that cause hematuria can also have a family history or be hereditary, such as idiopathic hypercalciuria and polycystic kidney; in addition, besides originating from the urinary system, there are other systemic diseases that can also cause hematuria, like tuberculosis, blood disorders, heart disease, lupus erythematosus, etc. Therefore, if you know any other history of disease or trauma, please don’t forget to tell your doctor when you visit him/her, as this will be helpful in analyzing the cause of hematuria. In addition, there are also some middle-aged and elderly people who always see an occult blood of (±) or have 1 (+) under the microscope during physical examination, without any symptoms, but repeatedly but just can’t find the cause of hematuria. If you have already undergone systematic examination and tumor exclusion, there is no need to worry too much, and this kind of asymptomatic microscopic hematuria is fine to pay attention to regular review.