I. Where does bilirubin in blood come from? The aging red blood cells release hemoglobin, which is broken down by liver cells into free bilirubin, which can only react indirectly with the reagents for examination, so it is called indirect bilirubin; indirect bilirubin is metabolized into water-soluble bilirubin in liver cells, which can react directly with the reagents for examination, so it is called direct bilirubin; these two types of bilirubin together are total bilirubin. bilirubin. Different diseases (liver disease or non-hepatic disease) will detect different bilirubin in the serum, from the detection of different bilirubin can distinguish different diseases, so first remember the difference between the two kinds of bilirubin. Does elevated bilirubin mean jaundice? Elevated bilirubin up to 85μmol/ml appears as yellowing of the eyes. Mild bilirubin elevation does not cause jaundice. The yellowing you see is only on the sides of the eyes, which are fatty pads, called pterygoid papillae in ophthalmology. Patients often say they have a yellow face, but it’s not a real “yellow” face. Third, can elevated bilirubin only be a liver disease? The function of red blood cells is to carry oxygen, and there are many of them, and their natural lifespan is about 120 days. Hemolytic disease has a large number of red blood cells destroyed, releasing a large amount of hemoglobin that exceeds the metabolic capacity of the liver cells, and elevated indirect bilirubin in the blood, evident as hemolytic jaundice. Jaundice occurs in all babies after birth because there is not enough oxygen in the mother’s tummy and a very large number of red blood cells are needed to get enough oxygen, after birth the breathing atmosphere does not need so many red blood cells and the excess is dissolved, this is called physiological hemolytic jaundice. In case of hemolytic disease (e.g., serum disease), a significant increase in indirect bilirubin or even jaundice and anemia must be seen by a hematologist. Direct bilirubin is a component of bile. If there is a bile stone obstruction in the bile duct, the bile secretion will not flow back into the blood, and the direct bilirubin in the blood will be elevated, which is obviously obstructive jaundice, and the patient must go to the hepatobiliary surgery department for consultation. Which type of bilirubin is elevated in liver disease? What is the jaundice called? Elevated serum aminotransferases are characteristic of hepatitis, and elevated aminotransferases mark inflammatory damage to liver cells. The inflammation and destruction of liver cells will affect the uptake and metabolism of indirect bilirubin and the secretion of direct bilirubin, which means that the function of each link from indirect bilirubin uptake into liver cells, to direct bilirubin, and then to direct bilirubin excretion from liver cells will be reduced. When both indirect and direct bilirubin are elevated in the blood, if jaundice develops, it is called hepatocellular jaundice. Hepatocellular jaundice occurs during the active phase of hepatitis. V. What is the cause of the elevated bilirubin in your blood? A high serum total bilirubin of more than 10 μmol/ml cannot be called “jaundice”. If the transaminases are not also elevated, it is not a “liver function abnormality”. In chronic hepatitis B virus carriers, mainly inactive carriers after hepatitis, there is a slight functional defect in the hepatocyte metabolism of bilirubin, which is not an expected factor in the development of the disease and does not affect health. The so-called “somatic bilirubin elevation” is quite widespread and no statistics are available in China, but it is reported in individual Western countries as 7% of the population. The above two are not liver disease bilirubin high, the magnitude of the high often fluctuates, related to rest, just this bilirubin high, can withstand any exertion. Six, what is the cause of your yellow urine again? Bile enters the intestinal lumen and direct bilirubin is also in it, which is hydrolyzed by bacterial enzymes in the colon to indirect bilirubin, which is later changed to fecal bilirubinogen, so the excreted feces is yellow, and if the feces is white, then it may be obstructive jaundice. A small amount of fecal bilirubin is absorbed by the small intestine and enters the liver together with indirect bilirubin, which is metabolized by the liver cells and excreted by the kidneys, so the urine also has a faint yellow color. The shade of urine color depends on the concentration of urine, such as morning urine, summer urine is more yellow, routine urine examination of urinary bilirubinogen (-), (±) or (1+) are normal, if ≥ (2+) is jaundice patients. Discharge from the feces is called fecal bilirubinogen, and discharge from the urine is called urobilinogen, in fact, the composition is the same, both are hemoglobin metabolized by the liver eventually by the urine, fecal discharge of waste.