According to the survey, the number of hepatitis B surface antigen carriers in China is estimated to be about 120 million, which is a very large number, of which about 30 million people have the disease and develop liver function fluctuations, that is, chronic hepatitis, and some of them even progress to cirrhosis and liver cancer. A correct understanding of the significance of hepatitis B serum markers (commonly known as hepatitis B “two-to-one”) and hepatitis B virus quantification can be of great help in judging the disease and formulating appropriate treatment plans, etc. So how should we interpret the hepatitis B “two-to-one” report? The report of hepatitis B “two pairs of half” should be interpreted. I. What is “two and a half”: What we usually call “two and a half” for hepatitis B refers to the surface antigen (HBsAg), surface antibody (HBsAb), e antigen (HBeAg), e antibody (HBeAb), core antibody (HBcAb) and these five items (HBcAb). HBcAb) these five items (Table 2-6). Readers can notice why there is no core antigen, it is because the core antigen is wrapped outside by surface antigen, generally not easy to detect in the serum, so generally do not do routine testing, which is the origin of the name “two and a half pairs”. The significance of each of them is described below. 1, surface antigen: this is the shell of the hepatitis B virus, is a specific sign of infection with hepatitis B, positive common in the incubation period and the onset of acute hepatitis B, asymptomatic hepatitis B virus carrier, chronic hepatitis B and related cirrhosis, liver cancer, etc.. Healthy adults with acute hepatitis B, 90% of patients with this antigen can be turned negative during the recovery period, such as persistent failure to turn negative means that the disease becomes chronic. 2, surface antibody: is a specific antibody produced by the body to the surface antigen, the surface antigen has a neutralizing effect, is a protective antibody, indicating that once infected with the hepatitis B virus, but whether or not there are symptoms, the body has been recovered and has a certain degree of immunity to the hepatitis B virus. Usually we inject hepatitis B vaccine to make this antibody positive. 3, e antigen: is a component of the core antigen, indicating that the virus has replication, acute hepatitis B, this is a transient positive, if continued positive indicates that the turn to chronic; in chronic hepatitis B, this positive often indicates that there is active replication of the virus, if this turns negative and e antibody turns positive, indicating that the virus replication is reduced or stopped. However, there is an exception, if the hepatitis B virus has a pre-C region variant, even if the e antigen is negative, the virus replication can often be detected. 4. e antibody: seen in the recovery phase of acute hepatitis B, which can mostly last for a long time; in chronic hepatitis B, the significance is as described above. It should be noted that this antibody is not protective, so a positive antibody does not mean that the body is immune to the hepatitis B virus. 5, core antibodies: this is the core antigen antibodies, and can be divided into core antibody IgM and IgG, clinical general detection of total antibody. In acute hepatitis B, these antibodies usually appear during the recovery period and can last for several years or longer, or even be positive for life. In chronic hepatitis B, the test needs to be combined with other markers. The significance of the core antibody IgM, which can sometimes be detected clinically alone, is that in acute hepatitis B, IgM is positive in high titers, especially in patients whose surface antigen has been converted to negative, and finding a positive IgM is very helpful in confirming the diagnosis of acute hepatitis B. If the IgM does not drop to normal within 1 year of acute hepatitis B, it suggests that the condition turns chronic. Second, what is often said about viral quantification: “PCR” and what is: hepatitis B virus quantification (HBVDNA quantification) is direct diagnostic evidence of how much hepatitis B virus is in the blood, positive indicates that the virus is replicating and is infectious. It is often used clinically to clarify the diagnosis, develop an antiviral treatment plan, and monitor the efficacy of antiviral therapy. The so-called “PCR” actually also refers to virus quantification, which is a quantitative test for HBVDNA (Table 2-7) and is referred to by some people as hepatitis B virus quantification. The above is a brief introduction to the significance of each of the “two pairs of half” and the quantification of the hepatitis B virus, but one should never judge the condition based on only one of the indicators, but should make a comprehensive judgment. Table 2-8 gives a brief description of the significance of the common combinations of the “two-and-a-half” tests. The above is only a list of some of the more common cases, but the disease varies greatly from person to person, and there may be different test results from the above combinations. In addition, it is best for patients with hepatitis B to have their hepatitis B virus quantified at the same time as their hepatitis B test for a comprehensive understanding of their condition.