What is the significance of urinary bilirubin, which often appears in routine urine tests? Bilirubin is a metabolic product of red blood cell destruction. Bilirubin and glucuronic acid combine to form conjugated bilirubin, which can pass through the glomerular membrane and be excreted in the urine due to its small molecular weight, which is the above-mentioned urinary bilirubin. However, urinary bilirubin cannot be detected in the urine of a normal person because the amount of conjugated bilirubin in the blood is very small. Positive urine bilirubin often indicates liver cell damage or biliary obstruction. Urine bilirubin found in routine physical examination should be alerted to liver diseases, such as acute and chronic hepatitis, cirrhosis. Biliary obstruction such as bile duct stones, pancreatic tumors, etc. Newborns should be alerted to the possibility of congenital diseases such as biliary atresia. In addition, hemolytic reactions caused by blood transfusion or hemolytic diseases caused by extensive burns may also appear positive for urinary bilirubin. Patients with jaundice are often accompanied by positive urine bilirubin and need to seek prompt medical attention to identify what is causing the disease. In summary, urinary bilirubin is negative in normal people, which means that it cannot be detected. Once it appears, it is recommended to seek medical attention for further examination to clarify the cause and treat it in a timely manner.