Laboratory Tests I. Biochemical Tests 1. Serum ALT and AST Serum ALT and AST levels generally reflect the degree of hepatocellular injury and are most commonly used. 2. Serum bilirubin Usually, serum bilirubin level is related to the degree of hepatocellular necrosis, but it should be distinguished from the elevated bilirubin caused by intrahepatic and extrahepatic cholestasis. Serum bilirubin in patients with liver failure may be progressively elevated, rising ≥1 times the upper limit of normal (ULN) per day, and may be ≥10×ULN; separation of bilirubin from ALT and AST may also occur. Xu Rulong, Department of Infectious Diseases, Nanchang Ninth Hospital, Nanchang, China 3, serum albumin Reflects the synthesizing function of the liver, patients with chronic hepatitis B, liver cirrhosis and liver failure may have decreased serum albumin. 4, Prothrombin time (PT) and PTA PT is an important indicator reflecting the function of hepatic coagulation factor synthesis, PTA is a commonly used method of PT measurement, which is of great value in judging the progress of the disease and the prognosis, and the recent progressive decrease of PTA to less than 40% is one of the important diagnostic criteria for liver failure, and <20% suggests a poor prognosis. There is also the use of International Normalized Ratio (INR) to express this index, INR value rise and PTA value decline has the same meaning. Cholinesterase can reflect the synthesis function of the liver, which is of reference value for understanding the severity of the disease and monitoring the development of liver disease. 6, alpha-fetoprotein (AFP) AFP obvious elevation is mainly seen in HCC, but it can also suggest the regeneration of hepatocytes after a large number of hepatocellular necrosis, so attention should be paid to the amplitude of AFP elevation, dynamic changes and its relationship with ALT, AST, and combined with the patient's clinical manifestations and results of liver ultrasonography and other imaging examinations for comprehensive analysis. HBV serology test HBV serological markers include HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc and anti-HBc-IgM. HBsAg positivity indicates HBV infection; anti-HBs is a protective antibody, and its positivity indicates immunity to HBV, which is seen in the recovery from hepatitis B and those who have been vaccinated for hepatitis B. HBsAg turning negative and anti-HBs turning positive is called HBV infection. HBsAg is negative and anti-HBs is positive, which is called HBsAg seroconversion; HBeAg is negative and anti-HBe is positive, which is called HBeAg seroconversion; anti-HBc-IgM is positive, which suggests the replication of HBV, which is mostly seen in the acute stage of hepatitis B, but can also be seen in the acute exacerbation of chronic hepatitis B; the total antibody of anti-HBc is anti-HBc-IgG, which is mostly positive as long as one has been infected with HBV, no matter whether the virus is cleared or not. Anti-HBc total antibody is mainly anti-HBc-IgG, which is positive whenever HBV infection has occurred, regardless of whether the virus has been cleared. In order to know whether there is simultaneous or overlapping infection of HBV and HDV, HDAg, anti-HDV, anti-HDV IgM and HDV RNA can be measured. HBV DNA, genotype and mutation detection 1, HBV DNA quantitative test can reflect the level of viral replication, which can be used for the diagnosis of chronic HBV infection, selection of therapeutic indications and judgment of the efficacy of antiviral therapy. The detection value of HBV DNA can be expressed as international unit (IU)/mL or copy/mL, and according to different detection methods, 1 IU is equivalent to 5.6 copies. HBV genotyping and detection of drug-resistant mutant strains Commonly used methods include: (1) genotype-specific primer PCR; (2) restriction fragment length polymorphism analysis (RFLP); (3) linear probe back-hybridization (INNO-LiPA); and (4) gene sequencing. Imaging diagnosis Ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) can be performed on the liver, gallbladder and spleen. The main objectives of imaging are to monitor the clinical progression of chronic hepatitis B, to understand the presence or absence of cirrhosis, to detect and identify the nature of space-occupying lesions, and in particular, to screen for and diagnose HCC. Liver elastography (hepatic elastography) has the advantage of being non-invasive, easy to perform, and repeatable, and is capable of identifying with relative accuracy mild hepatic fibrosis and severe hepatic fibrosis/ Early cirrhosis. However, its success rate is affected by factors such as obesity and the size of the intercostal space, and its value is affected by hepatic steatosis, inflammatory necrosis, and cholestasis, and it is not easy to accurately differentiate between two adjacent grades of hepatic fibrosis. Pathologic Diagnosis The purpose of liver tissue biopsy is to assess the extent of liver disease in patients with chronic hepatitis B, to exclude other liver diseases, to determine prognosis, and to monitor treatment response. The pathology of chronic hepatitis B is characterized by obvious inflammation in and around the confluent area, and the infiltrating inflammatory cells are mainly lymphocytes, with a small number of plasma cells and macrophages; the aggregation of inflammatory cells often causes the confluent area to expand, and can destroy the boundary plate causing interface hepatitis, also known as piecemeal necrosis. Degeneration and necrosis of hepatocytes in the lobules, including fusional necrosis and bridging necrosis, etc., can also be seen, which becomes more and more obvious with the aggravation of the lesion. Inflammatory necrosis of the liver can lead to excessive collagen deposition and formation of fibrous septa. If the lesion is further aggravated, it may cause structural disorganization of hepatic lobules, pseudolobule formation and eventually progression to cirrhosis. The histologic diagnosis of chronic hepatitis B includes pathogenesis, activity of inflammatory necrosis and degree of hepatic fibrosis. The grading of hepatic tissue inflammatory necrosis (G1~4) and the staging of the degree of fibrosis (S1~4).