There are often patients who ask: Doctor, my physical examination report found that the urine occult blood has a plus sign, do I have kidney disease? First of all, we need to rule out a series of interfering factors of urine occult blood. What are the interfering factors? Urine red blood cell microscopy count: There are many interfering factors in the routine urine occult blood test, so the first thing we have to do is not to rush to the conclusion of the disease, but to see whether the patient’s urine routine urine microscopy count. If the urine has a plus sign but the urine red blood cell count is within the normal range (normal human urine red blood cell count is 0-3 under high magnification), it often means that there is not a problem with the urinary system itself, but most likely some kind of contamination of the retained specimen, such as urinary tract inflammation, female urinary tract infection, gynecological inflammation, which can interfere with the urine specimen and cause a positive urine occult blood. This is not called hematuria and is not the same thing as clinical nephritis. Therefore, if your laboratory tests reveal that the urine occult blood has a plus sign, but the red blood cell microscopy count is within the normal range, we should not be alarmed, this situation is often not kidney disease. If the urine occult blood has a plus sign and the red blood cell count exceeds the normal value (more than three under high magnification), you may need to come to the nephrology department for examination. Distinguish between intra-renal and extra-urinary diseases: Patients come to the doctor with a checklist confirming that they have positive urine red blood cells, then the doctor will first explain to the patient the reasons for the red blood cells in the urine, which are often divided into two main categories: 1) nephrology problems, such as what we often call nephritis or glomerulonephritis; 2) urological problems; the two cases should be distinguished, because the medical and surgical treatment directions for kidney disease are completely different the direction of treatment. So how to distinguish? This method is relatively simple, which is the phase difference examination of urine red blood cells, or morphological examination of urine red blood cells, which helps us determine whether the urine red blood cell morphology is normal through aberration microscopy. 1, urine red blood cell morphology is normal The red blood cells in the blood are disc-shaped, oval, if you find that the urine red blood cells look the same as the red blood cells, this bleeding site is often related to urology, especially in the urinary system below the kidneys, such as ureteral children, bladder, men’s prostate and other parts, may be due to inflammation, tumors, stones. 2, urine red blood cell form is not normal If the red blood cells in the urine is not the normal form, and blood red blood cell form is not the same, this may be related to nephrology disease, because there is inflammation inside the kidney, red blood cells must be filtered through the glomerulus excretion, the process has undergone extrusion caused by changes in form. This is the time to be especially vigilant, may be closely related to the nephrology glomerulonephritis, need to come to the nephrology department to find the cause of nephritis. 3, find other cells In many cases, the urine red blood cells will also see a variety of other cells, such as white blood cells, and even epithelial cells, in this case, we still do not rush to conclude, because in the urinary tract infection or gynecological inflammation interference in the case of routine urine examination may appear some cells that are not in the urine should have. The presence of such cells may often be simply a contamination of the urine specimen, and care must be taken to standardize the retention of urine. The true clinical picture: A final point is worth making. The real clinical situation is often complex, and a urine microscopic examination of red blood cells may reveal not a single red blood cell that is all deformed or all non-deformed, but often a mixture of them. In this case, how should we deal with it? It depends on the proportion of deformed and non-deformed, and it is generally considered that if the proportion of a certain form accounts for more than 70% of all forms, we consider the condition to be dominant. For example, if the deformed red blood cells exceed 70%, we can judge that it is a nephrology problem. To sum up: 1, urine occult blood with a plus sign, do not need to worry, to be at the same time through the urine red blood cell microscopy count to comprehensive judgment 2, kidney disease is divided into nephrology and urology, can be partitioned by the urine red blood cell phase difference examination, red blood cell morphology is normal for urological disease, non-normal for nephrology disease.