1.What is hematuria? Normal urine has no red blood cells or occasionally a small amount of red blood cells. When urine sediment is taken for microscopic examination after centrifugation, red blood cells ≥3/HPF is called microscopic hematuria. 2.What is the significance of urinary occult blood? Red blood cells have hemoglobin, which has peroxidase activity and can oxidize the relevant pigment to make it colorful, and the urine test paper has an oxidized substrate of hemoglobin. The method can react on both intact red blood cells and free hemoglobin or myoglobin. Therefore, there are several possibilities for a positive urine occult blood: Urinary erythrocyte increase: hematuria Urinary hemoglobin increase: hemoglobinuria, such as hemolysis Urinary myoglobin increase: myoglobinuria, such as muscle damage False positive: some non-heat resistant enzymes in food can produce a false positive 3, the relationship between a positive urinary occult blood and microscopic findings? There is no absolute correspondence, but there is a correlation between urine test paper test as a screening tool and urine sediment microscopy. Hematuria can be expressed as flesh-washing water-like urine, cola-colored urine, tea-colored urine, etc. Red urine is not equal to hematuria Hemoglobinuria and myoglobinuria can lead to deep red urine, resembling soy sauce color Increased uric acid salts in urine can lead to pink urine, mostly seen in small infants Taking pumpkin, orange and other food containing more pigment can lead to red urine Taking furantoin and metronidazole can lead to brown urine Taking rifampin can lead to red urine 5. Where do the red blood cells in urine come from? Glomeruli: such as various glomerular diseases Renal vessels: such as trauma, renal artery or vein thrombosis, coagulopathy, thrombocytopenia, left renal vein compression syndrome, etc. Urinary tract: urinary tract infection, hemorrhagic cystitis (adenovirus, cyclophosphamide), hypercalciuria, urinary stones, tumors, strenuous exercise, etc. Interstitial kidney: hydronephrosis, cystic kidney disease, interstitial nephritis, etc. Other: vaginal or lower gastrointestinal bleeding Mixed in Therefore, hematuria is not equivalent to glomerulonephritis