[Medical Q&A] Does a positive hepatitis B virus surface antigen mean that you have hepatitis B?

Planner: Chinese Medical Association

Reviewer: Ning Yongzhong, Chief Technician, Beijing Chuiyangliu Hospital

A positive hepatitis B surface antigen (HBsAg) usually indicates the presence of hepatitis B virus in the body, but it does not necessarily mean that you have hepatitis B.

1. Possible causes of HBsAg positivity

(1) Some people may be carriers, meaning they have the hepatitis B virus in their bodies but do not have obvious liver damage or symptoms.

(2) When first infected with hepatitis B virus, HBsAg will be positive, but the immune system of most adults is able to clear the virus.

(3) If HBsAg remains positive for more than 6 months, it is considered chronic hepatitis B infection, which requires close attention and treatment.

2. Hepatitis B related testing items (including but not limited to the following items)

(1) Hepatitis B serum marker detection: including HBsAg, anti-HBs, HBeAg, anti-HBe, anti-HBc and anti-HBc IgM.

(2) Quantitative detection of hepatitis B virus nucleic acid, detection of hepatitis B virus typing, and detection of hepatitis B virus drug-resistant mutation.

(3) Biochemical liver function tests: including serum enzyme assay, serum protein assay, bilirubin metabolism assay, etc.

(4) Coagulation function tests: including prothrombin time, prothrombin activity, international normalized ratio, fibrinogen, activated partial thromboplastin time, thrombin time, etc.

(5) Tumor marker testing for liver cancer: including AFP, vitamin K deficiency or abnormal prothrombin, etc.

The diagnosis of viral hepatitis includes clinical symptoms, signs, auxiliary examinations and response to treatment. The diagnosis of laboratory tests requires the support of many test results. If only a single test is positive, viral hepatitis cannot be diagnosed. If the test result shows that HBsAg is positive, it is recommended to seek medical attention in time and have a professional doctor conduct a comprehensive examination and evaluation.