What is meant by hematuria: An increase in the excretion of red blood cells in urine, ≥3 red blood cells per high-powered microscopic field of view in centrifuged precipitated urine, or more than 1 in non-centrifuged urine or more than 100,000 in 1-hour urine red blood cell count, or more than 500,000 in 12-hour urine sediment count, all indicate an abnormal increase in red blood cells in urine, and are called hematuria. If the increase in red blood cells is found only microscopically, it is called microscopic hematuria; if it is visible to the naked eye (washed water-like or containing blood clots), it is called carnal hematuria. Whether hematuria is harmful or not: Usually 1mL of blood per 1000ml of urine is visible to the naked eye, so for those who urinate 1000ml daily, the blood excreted through the urine is only a few milliliters, which is insignificant compared to the harmfulness of proteinuria, especially large amounts of proteinuria. The harmfulness of hematuria is indirect.