Surface antigen 400IU/ml is on the high side, suggesting that the number of hepatitis B virus is high, and there may be hepatitis B virus infection, and further examination of viral DNA and liver function should be carried out. Surface antigen generally refers to hepatitis B surface antigen, is one of the five items of hepatitis B, different medical institutions test normal value is different, generally speaking, hepatitis B surface antigen 400IU/ml is high, the clinical significance is to suggest that the patient may be infected with hepatitis B virus, but also need to be combined with the hepatitis B viral DNA and liver function tests to determine the infectiousness of the presence of the liver function tests, whether it is necessary to treat and so on. If you find that the hepatitis B surface antigen is high, you need to consult a doctor in time, make an early diagnosis after clarifying the condition, and treat it as early as possible to prevent it from turning into chronic hepatitis and cirrhosis.