What are the misunderstandings about hepatitis B surface antigen?

When checking for hepatitis B in the hospital, there are generally five tests. Hepatitis B surface antigen is one of the five tests. This test is mainly used to check whether the hepatitis B virus is infected, which is closely related to our health. Generally speaking, the test results are positive and negative. If it is positive, it means that there are some problems with hepatitis B and further examination and treatment are needed. However, many people may not know much about hepatitis B surface antigen and may have many misunderstandings.

Misconception 1: Acute hepatitis with positive surface antigen is definitely hepatitis B, and acute hepatitis with negative surface antigen is not hepatitis B.

In clinical practice, we often encounter patients with positive hepatitis B surface antigen accompanied by jaundice and elevated alanine aminotransferase, and doctors will naturally consider the possibility of hepatitis B. However, jaundice and elevated alanine aminotransferase are non-specific and can occur as long as liver cells are damaged, leading to abnormal liver function. Similar situations may also occur in hepatitis B surface antigen carriers who are infected with other types of hepatitis or combined with certain bacteria, rickettsial infection, etc. caused by hepatitis.

Misconception 2: Using the surface antigen titer to determine whether the virus is contagious.

The surface antigen is the capsid protein of the hepatitis B virus and does not contain viral nucleic acid. Therefore, the surface antigen itself is not contagious, and the level of its titer does not represent whether it is contagious or not. However, surface antigen-positive serum, regardless of its titer, may contain infectious doses of virus particles. Some people have diluted surface antigen and e-antigen-positive serum tens of millions of times and it is still infectious. At this time, using a very sensitive method to detect surface antigen, the result is negative.

Misconception 3: Using the level of surface antigen titer as an indicator to evaluate the condition and efficacy of treatment.

The surface antigen is the coat protein of the hepatitis B virus. Its titer may fluctuate frequently, and there is no direct relationship between the titer and the disease condition. Many people with the same surface antigen titer may be asymptomatic carriers of hepatitis B virus, or they may have chronic active hepatitis or even cirrhosis or liver cancer.