What is the cause of red blood cells in urine test?

Generally speaking, there are no red blood cells in the urine of normal people, because red blood cells do not exist in the urine environment at all. However, some people find red blood cells in their urine during physical examinations. What is going on? Ordinary people don’t understand these test results very well, let alone the reasons. So, today I will explain this knowledge to you.

High red blood cell count in urine routine examination may be a sign of serious disease in the urinary system. Hematuria is defined as the presence of ≥3 red blood cells per high-power field of view in centrifuged urine, or more than 1 red blood cell count in non-centrifuged urine or more than 100,000 in 1-hour urine, or more than 500,000 in 12-hour urine sediment, all indicating an abnormal increase in red blood cells in the urine. In mild cases, only an increase in red blood cells is found under the microscope, which is called microscopic hematuria; in severe cases, the appearance of the urine is like meat washing water or contains blood clots, which is called macroscopic hematuria. Usually, when there is 1 mL of blood per liter of urine, it can be seen with the naked eye, and the urine appears red or like meat washing water.

More than 95% of hematuria is caused by diseases of the urinary system itself, among which glomerular diseases of the kidney (acute nephritis, rapidly progressive nephritis, membranoproliferative nephritis, mesangial proliferative nephritis, focal glomerulosclerosis, etc.), kidney cysts larger than 2 cm, stones (kidney, ureter, bladder, urethral stones), prostate hyperplasia, urinary tract infections (tuberculosis, pyelonephritis, cystourethritis, prostatitis) and tumors (kidney, ureter, bladder, prostate tumors) are the most common.

Other diseases such as coagulation disorders (idiopathic or drug-induced thrombocytopenia, hemophilia, scurvy, etc.) and systemic diseases (aplastic anemia, leukemia, systemic lupus erythematosus, dermatomyositis, leptospirosis, epidemic hemorrhagic fever, etc.) can also cause hematuria.

Also check the kidneys and urinary system. Bacteria are not important. The confirmation mainly depends on the number of white blood cells.

The presence of red blood cells in urine tests is an important message, telling everyone that there is a problem with the body. It may be a kidney disease or a blood disease. The test results need to be further confirmed. In short, once red blood cells are found in urine, we should be mentally prepared and face it positively.