From the Guidelines
HBsAg (Hepatitis B surface antigen) is a protein found on the surface of the hepatitis B virus that indicates active hepatitis B infection, and its presence in blood tests typically means the person has an acute or chronic hepatitis B infection, as confirmed by the most recent study 1. When detected in blood tests, HBsAg typically means the person has an acute or chronic hepatitis B infection. HBsAg appears in the blood 1-10 weeks after exposure to the virus and, if it persists for more than 6 months, indicates chronic infection.
Key Points to Consider
- Testing for HBsAg is part of standard hepatitis B screening, often accompanied by tests for antibodies (anti-HBs and anti-HBc) to determine infection status.
- For those who test positive, further evaluation including HBeAg, anti-HBe, HBV DNA levels, and liver function tests are recommended to assess disease activity and guide treatment decisions, as outlined in the study 2.
- Chronic HBsAg-positive patients should be monitored regularly for liver disease progression and may require antiviral medications like entecavir, tenofovir, or pegylated interferon depending on viral load, liver enzyme levels, and evidence of liver damage.
- HBsAg positivity also indicates the person is potentially infectious to others, so precautions should be taken to prevent transmission, as noted in the study 3.
Important Considerations for Patient Care
- Patients with chronic hepatitis B should undergo testing for IgG anti-HAV, and all patients with a negative immune status for hepatitis A should receive HAV vaccine, as recommended in the study 2.
- Laboratory tests should include tests for coinfection with HCV and/or HIV in those at risk, as suggested in the study 4.
- The management of chronic hepatitis B should be guided by the most recent clinical practice guidelines, which emphasize the importance of regular monitoring and individualized treatment plans, as outlined in the study 1.
From the Research
HBsAg Overview
- HBsAg (Hepatitis B surface antigen) is a protein on the surface of the Hepatitis B virus (HBV) 5
- It is used as a marker to detect HBV infection 5
- The presence of HBsAg in the blood indicates that a person is infected with HBV 5
HBsAg and Treatment Outcomes
- Long-term entecavir therapy can lead to a continuous reduction of serum HBsAg levels beyond suppression of HBV DNA 5
- A study found that 16.7% of patients lost HBeAg after 8-13 years of therapy, but not HBsAg 5
- Another study found that entecavir plus low-dose, on-demand hepatitis B immunoglobulin (HBIg) resulted in a low rate of HBV recurrence without evidence of resistance development 6
HBsAg Seroclearance
- Seroclearance of HBsAg is associated with improved patient outcomes, including reduced risk of hepatocellular carcinoma (HCC), liver decompensation, and liver transplantation 7
- A meta-analysis found that the pooled rate ratios for the HBsAg seroclearance group were 0.28 for liver decompensation, 0.30 for HCC, and 0.22 for liver transplantation and/or death 7
- HBsAg seroclearance is considered a desirable endpoint of treatment for chronic HBV infection 7
Quantitative HBsAg Levels
- Quantitative HBsAg levels can be used to monitor treatment response in patients with chronic HBV infection 8
- A study found that there was an overall decline in HBsAg levels from baseline to year 1 to year 2 in patients treated with entecavir 8
- However, the majority of patients did not show significant decline in HBsAg levels despite HBV DNA suppression 8