Examined Items Basic Functions Synthesis Alb, PT, Lipids and Lipoprotein Excretion Bilirubin, Bile Acids, Pigments (Sodium Sulphobromophthalein, Indocyanine Green) Excretion Metabolism Metabolic Immunity of aminophenazone, finasteride, tryptophan, and urea Gamma-globulin Markers Hepatocellular Injury -Enzymatic Alterations ALT, AST, LDH, adenosine deaminating acid cholestatic Bilirubin, Bile Acids, Cholesterol, ALP, and GGT, Cirrhosis Collagen types III, VI, I, and IV, hyaluronic acid, proline hydroxylase Hepatocellular carcinoma AFP, GGT-II, AFU, AKP-I, aldolase A, decarboxylated thrombin Autoimmune Hepatitis Smooth Muscle Antibodies Primary Biliary Cirrhosis Mitochondrial Antibodies, IgM Reflective of Hepatocellular Damage are commonly used in serum enzyme assays: glutamatergic aminotransferase ALT (GPT), glutamate aminotransferase AST ( GOT), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT or GGT), etc. All of these enzymes are found in liver cells. All of these enzymes are present in hepatocytes, and their entry into the serum increases when the hepatocyte membrane is damaged or the cells are necrotic. By measuring the activity of the enzymes in the serum or plasma, the damage to the hepatocytes and the degree of damage can be reflected. Among the various enzyme tests, ALT and AST can sensitively reflect the damage of hepatocytes and the degree of damage. Serum ALT is the most sensitive in acute viral hepatitis, drug or alcohol induced acute hepatocellular injury. In chronic hepatitis and cirrhosis, AST increases more than ALT, so AST mainly reflects the degree of liver injury. In severe hepatitis, due to a large number of hepatocellular necrosis, ALT in the blood gradually decreases, but at this time bilirubin is progressively increased, i.e., there is a phenomenon of “bilirubin separation”, which is often a precursor of liver necrosis. In the recovery period of acute hepatitis, if ALT is normal and γ-GT is continuously elevated, it often suggests chronic hepatitis. In chronic hepatitis, if γ-GT continues to exceed the normal reference value, it suggests that chronic hepatitis is in an active stage. In patients with alcoholic liver disease, the activity of AST is also often greater than that of ALT. ALT and AST are mainly distributed in the hepatocytes of the liver, and both have normal values of 0-40 international units. Alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGT or gamma-GT) are commonly used in the diagnosis of biliary system diseases. Total bilirubin (TBil) and direct bilirubin (DBil), which reflect the secretion and excretion function of the liver, can be elevated when suffering from viral hepatitis, drug- or alcohol-induced toxic hepatitis, hemolytic jaundice, and internal bleeding. Elevated direct bilirubin indicates an obstruction to the elimination of bilirubin after its processing by the liver cells, i.e., biliary obstruction occurs. The life span of human red blood cells is usually 100 to 120 days. After the red blood cells die, they become indirect bilirubin, which is converted by the liver into direct bilirubin, which makes up bile and is excreted into the biliary tract and finally through the stool. The sum of indirect bilirubin and direct bilirubin is total bilirubin. A disorder in any of the above can cause a person to become jaundiced. Hemolytic jaundice can occur if too many red blood cells are destroyed and too much indirect bilirubin is produced, and the liver is unable to convert it completely into direct bilirubin; hepatocellular jaundice occurs when the liver cells become diseased, either because bilirubin cannot be converted into bile normally, or because of the swelling of the liver cells, which presses the bile ducts within the liver and obstructs the excretion of bile, thus elevating bilirubin in the blood; and once a tumor or stone develops in the biliary system outside of the liver, jaundice will occur. system develops a tumor or stones appear, blocking the bile ducts, bile can not be excreted smoothly, and obstructive jaundice occurs. Jaundice in patients with hepatitis is usually hepatocellular jaundice, which means that both direct and indirect bilirubin are elevated, while direct bilirubin is predominantly elevated in patients with biliary hepatitis. The normal value of total bilirubin is 1,71-17,1 μmol/L (1-10mg/L), and the normal value of direct bilirubin is 1,71-7 μmol/L (1-4mg/L). Items reflecting the synthetic storage function of the liver Indicators reflecting the synthetic metabolic function of the hepatocytes: total protein (TP), albumin (ALB), immunoglobulin G, and prothrombin time (PT). Once the synthetic function of the liver decreases, the concentration of the above indicators in the blood decreases, and the degree of decrease is positively correlated with the degree of damage to the synthetic function of the liver. Serum musk turbidity test, abbreviated as TTT, reflects the degree of liver parenchymal damage, and is also a qualitative test of liver protein metabolism dysfunction, and its degree of elevation is basically parallel to the degree of liver damage. Albumin is produced in the liver, when liver function is impaired, the production of albumin decreases, and the degree of decrease is parallel to the severity of hepatitis. Serum albumin concentration is reduced in patients with chronic and severe hepatitis and cirrhosis. Albumin plays a role in the body in nourishing cells and maintaining intravascular osmotic pressure. When albumin decreases, intravascular osmotic pressure decreases and patients may develop ascites. Globulin is produced by the body’s immune organs. When antigens (enemies) such as viruses are present in the body, the body’s immune organs have to be reinforced to destroy the enemies. As a result, globulin production increases. The normal value of serum albumin is 35-50 g/L, globulin is 20-30 g/L, and the A/G ratio is 1,3-2,5. Items reflecting liver fibrosis and cirrhosis Patients with chronic hepatitis and cirrhosis have a decrease in the production of albumin and a concomitant increase in the production of globulin, resulting in an inverted A/G ratio. G ratio inversion. In patients with chronic hepatitis B, a chronic inverted albumin-globulin ratio alerts to signs of cirrhosis. The level of albumin reflects the number of normal liver cells to a certain extent. If the albumin value decreases gradually during the course of the disease, it indicates a more serious condition with a poor prognosis; a rise in albumin value after treatment suggests that the treatment is effective; when the albumin value decreases to less than 25g/L, ascites is likely to occur. Elevated globulin value generally indicates inflammatory changes within the liver. When the A/G ratio is less than 1, it is called inverted A/G ratio. When the disease worsens, the A/G ratio decreases. If inverted, it often indicates chronic substantial liver damage and a poor prognosis. Prolonged prothrombin time (PT) reveals a decreased ability of the liver to synthesize various clotting factors. Liver is the main site of blood clotting factors, when the activity of prothrombin decreases, it often reflects the degree of damage to the liver cells, which often causes bleeding, bruising and other clinical manifestations. The normal A/G ratio is 1,3-2,5. AFP, a serum marker reflecting liver tumors, is a biochemical test for the diagnosis of primary hepatocellular carcinoma. Although alpha-fetoprotein (AFP) is elevated, most patients with hepatocellular carcinoma have no obvious symptoms at this time. However, AFP is also elevated in a few cases of hepatitis and cirrhosis, and gonadal malignancies, but the magnitude of elevation is not as high as that of primary liver cancer. In addition, some patients with hepatocellular carcinoma may have normal value of alpha-fetoprotein, so imaging examinations such as ultrasound, CT, magnetic resonance imaging (MRI) and liver angiography should be performed at the same time to increase the reliability of diagnosis. First, liver synthesis function (a) Albumin (Alb) liver is the only place to synthesize albumin, serum albumin level is one of the good indicators to reflect chronic liver injury. Reduced serum albumin level can be seen in: insufficient nutritional intake, impaired synthesis, excessive consumption and increased loss. The serum albumin level of patients with chronic liver disease can reflect the liver’s ability to synthesize albumin and changes in the volumetric distribution of albumin. If the serum albumin level decreases and is not easy to recover, the prognosis is often poor. （When liver function is impaired, the related coagulation factor synthesis is impaired, which can lead to prolongation of PT, which is one of the early predictive indicators of liver function abnormality. prolongation of PT, and vitamin K cannot be corrected, which is a sign of very poor liver function. In fulminant hepatic failure, PT is an important early diagnostic indicator. （Lipids and lipoproteins are not sensitive indicators of liver damage, but serum cholesterol ester levels decrease during hepatocellular damage and are proportional to the degree of liver damage. In chronic liver disease, lipoprotein decreases, and its level is negatively correlated with aminotransferases and bilirubin. Second, the excretory function of the liver bilirubin bilirubin is one of the important indicators of liver function, the normal level of total bilirubin TBIL <1,1mg/dl (17,1μmol/l), 70% of which is indirect bilirubin, which can not be filtered from the kidney. Only direct bilirubin can be excreted from the urine. Note: 1. TBIL < 5 times normal (85 μmol/l) in hemolytic jaundice when liver function is normal.2. TBIL < 500 μmol/l in jaundice of any cause when renal function is normal.3. Jaundice is present, but urinary bilirubin is negative, which means that it is an elevation of indirect bilirubin.4. Many jaundices in which the predominant cause of jaundice is purely an elevation of indirect bilirubin are Gilbert This syndrome has no pathological tissue changes in the liver tissue and has no obvious effect on the organism, so no special treatment is usually needed. Third, serum enzyme levels (a) ALT, ASTALT specificity is better than AST. 1, when ALT > 10 times normal, certainly have liver damage (such as chronic hepatitis B) 2, biliary tract disease, ALT, AST is elevated, but < 8 times normal 3, AST / ALT ratio: (1) estimate the degree of liver damage: the larger, the more serious the damage; (2) identification of liver disease: alcoholic hepatitis > 2, chronic hepatitis B > 1 may be hepatic fibrosis or cirrhosis (b) alkaline phosphatase ALP1, ALP >4 times normal: cholestasis syndrome 2, ALP>2, 5 times normal, ALT, AST<8 times normal: 90% for cholestasis 3, ALP>2, 5 times normal, ALT, AST>8 times normal: 90% for viral hepatitis (3) Glutamyl transpeptidase GGT 90% of patients with hepatobiliary disorders have elevated GGT, GGT>10 times normal, mostly due to alcoholic liver, intra-hepatic, extra-hepatic cholestasis, primary hepatocellular carcinoma. Biliary sludge, primary liver cancer, liver enzymes evaluation 1, the British large sample of healthy population survey found that: 6% of the asymptomatic normal population ALT, AST elevated, 5% of the normal population of all test results in the “normal value” outside the range. Therefore, some abnormal liver test results are not really abnormal. 2. The treatment of elevated single transaminase level is: check again, if the elevation is more than two times of normal, further examination is needed.