In clinical practice, we often see patients who do not understand what “hematuria” is all about and take the “urine occult blood” or “urine occult blood” in the laboratory test sheet with several “+ The “occult urine blood” or “occult urine blood” in the test results are taken as hematuria, and they worry and worry about this. What is the relationship and difference between “urinary occult blood” and “hematuria”? It turns out that “hematuria” refers to the presence of red blood cells in the urine, which originally existed in the blood, but for various reasons ran into the urine, red blood cells were found in the urine before it could be called “hematuria”, and the discovery of red blood cells depends on The detection of red blood cells depends on the microscope, and the test results are made by the examiner or a special computer identification system. “Urine occult blood” is a test for hemoglobin in urine, which is only the main structural component of red blood cells, a natural red pigment protein, and the reason why red blood cells (blood) are red. The intact red blood cells do not release hemoglobin until after they have been destroyed. In patients with hemolytic diseases (e.g., serum sickness, thalassemia), if the red blood cells are destroyed, hemoglobin is released into the blood, and when the amount of free hemoglobin in the blood is high, part of the hemoglobin will run into the urine, and at this time, urine tests can detect “urine occult blood (urine occult blood)”, but urine red blood cells The test is not available (unless the patient also has hematuria). On the other hand, modern testing techniques often use indirect methods to detect “hematuria” for convenience and speed, by detecting hemoglobin, the main component of red blood cells, and if hemoglobin is present, it is “urinary occult blood “If hemoglobin is present, it is a positive urine occult blood (+), and if hemoglobin is not present, it is a negative urine occult blood (-). In this way, patients with the hemolytic disease mentioned earlier can also have positive urine occult blood, which is obviously not what we call “hematuria”, but is medically known as “hemoglobinuria”. There are other conditions that can cause “positive urine occult blood”, such as the presence of myoglobin in the urine (which is present in muscle cells and can be released into the urine in cases of seismic stress or muscle disease), which can also cause “positive urine occult blood”, called “myoglobinuria”. Therefore, simply put, “urine occult blood” is only a “potential hematuria” and not necessarily true hematuria! The “urine occult blood” item in the “urinalysis” of the computerized automated system can only be used as a test for “hemoglobinuria” and a screening test for hematuria, and the diagnosis of true hematuria relies on direct The real diagnosis of hematuria relies on the direct detection of urine red blood cells! There is one more thing to remind you: there are times when urine occult blood is “false positive”! In addition to the aforementioned hemoglobinuria, myoglobinuria and true hematuria, which can appear as a true positive urine occult blood test, a false positive urine occult blood test can also occur in the following cases: (1) reasons for testing equipment: urine analysis equipment is overly sensitive, urine test strips are out of date, deteriorated, etc.; (2) reasons for urine samples: urine contains bacteria (bacteria urine itself, or urine is not freshly contaminated with bacteria ), contains oxidizing substances or contains enzymes that can make peroxide decomposition, etc. Therefore, there is no need to worry blindly when you see urine test results with urine occult blood several (+), but to analyze and find possible causes with the help of the attending doctor and listen to the doctor’s explanation.