What is the normal HBsAg level?

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This article is written under the professional supervision of Msc., Dr. Tran Thi Vuong - Microbiology doctor- Department of Medical Laboratory - Vinmec International General Hospital Hai Phong.

HBsAg level is used for classification, monitoring, and prognosis of hepatitis B liver infection. HBsAg test is also for diagnosing HBV liver infection. 

1. What is the HBsAg level?

HBsAg is abbreviated for Hepatitis B surface antigen. If a patient is positive for HBsAg (HBsAg+), this surface antigen is present in their blood, which means they are carrying the HBV virus.

On the other hand, if the patient is HBsAg negative (HBsAg-), they do not have HBV virus in their blood. Normally, HBsAg appears in the blood after 1 to 8 weeks of exposure to HBV.

HBsAg result indicates the Hepatitis B virus’s surface antigen level. This test is thus used to examine the presence of this virus and whether the patient is infected, but not to assess its activity in the body.

According to specialists, all acute Hepatitis B patients are positive with HBsAg. Over time, the infection can terminated by anti-HBs and HBsAg can disappear. However, for 10 - 15% of patients, the disease can progress into a chronic stage, potentially leading to cirrhosis and liver cancer.

Trắc nghiệm: Làm thế nào để bảo vệ lá gan khỏe mạnh? Làm test trắc nghiệm kiểm tra hiểu biết về gan có thể giúp bạn nhận thức rõ vai trò quan trọng của gan, từ đó có các biện pháp bảo vệ gan để phòng ngừa bệnh tật.

2. What is the normal HBsAg level?

For automated HBsAg tests using automated immunoassay machines, the result coming out would be a number. A value above the set point would be interpreted as positive, while one below that point is considered negative. Most of these machines, regardless of brand, have the set point value of 1.0 SO or COI. Therefore, a result below 1.0 SO or COI (<1.0) is normal and negative. On the other hand, a level of above 1.0 SO or COI (>1.0) is positive.

HBsAg level of <1.0 SO/COI is normal
HBsAg level of <1.0 SO/COI is normal

In case of negative or normal HBsAg level, the patient is not infected with Hepatitis B virus. If the HBsAg antibody test shows a negative result, vaccination against Hepatitis B is recommended. If having a positive HBsAg antibody test result, the patient is thus immune to Hepatitis B or has recovered from a past Hepatitis B virus infection. 

In case of positive HBsAg level, additional tests are recommended to confirm the treatment plan, such as HBeAg, HBV-DNA, liver function test, liver ultrasound, etc. The patient would also need to consult with their specialists for effective treatment and monitoring. 

HBsAg test
HBsAg test

3. Important notes when receiving the test result.

There are certain matters that patients need to pay attention to:

  • Not all positive HBsAg test confirms that you are having Hepatitis B disease. According to specialists, HBsAg (+) results are very common in Vietnam, as on average, 2 out of every 10 people tested can receive a positive result.  
  • When receiving a positive HBsAg test result, have your family members tested for HBsAg to check if they also have the infection.
  • If you are infected with Hepatitis B virus during pregnancy, the baby must receive its shots within 12 hours after being born. Avoid breastfeeding as the virus can be passed to the baby via breast milk.
  • Family members should not share personal items such as toothbrushes, towels, shaves, bathtubs,... with Hepatitis B patients. Inform your partner about your condition and do not engage in sexual activity without protection. 
Be aware of hepatitis B prevention
Be aware of hepatitis B prevention

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