From the Guidelines
A positive core hepatitis B antibody (anti-HBc) with a negative surface antigen (HBsAg) typically indicates either a past resolved hepatitis B infection or a false positive result, with the most likely interpretation being recovery from past infection and immunity, as indicated by the presence of anti-HBc and the absence of HBsAg 1. This pattern means your body has developed antibodies against the core of the hepatitis B virus, but the virus itself is not actively replicating in your liver. Most commonly, this represents a previous infection that your immune system successfully cleared. Your liver is likely healthy now, and you are not infectious to others. However, in some cases, this pattern could indicate a "window period" (rare) where HBsAg has disappeared but surface antibodies haven't yet developed, or an occult hepatitis B infection with very low viral levels. To clarify your specific situation, additional testing is recommended, including hepatitis B surface antibody (anti-HBs) and possibly HBV DNA, as suggested by the guidelines for the prevention of hepatitis B virus infection 1. If anti-HBs is positive, you have immunity from past infection. If negative, your doctor might consider HBV DNA testing to rule out occult infection, especially if you have liver disease, are immunocompromised, or need immunosuppressive therapy, as outlined in the guide to utilization of the microbiology laboratory for diagnosis of infectious diseases 1. It's also important to note that the presence of anti-HBc is the only serologic marker detected in some individuals, which can be due to various reasons, including recovered but waned anti-HBs levels or circulating HBsAg that is not detectable by laboratory assays 1. In such cases, HBV DNA testing may be necessary to determine the presence of infection. Overall, the interpretation of a positive anti-HBc and negative HBsAg result requires careful consideration of the individual's clinical context and additional testing to determine the presence of immunity or infection. Key points to consider include:
- The presence of anti-HBc indicates exposure to hepatitis B virus
- The absence of HBsAg suggests that the virus is not actively replicating
- Additional testing, including anti-HBs and HBV DNA, is necessary to determine immunity or infection
- Clinical context, such as liver disease or immunocompromised status, should be considered when interpreting test results.
From the Research
Interpretation of Serological Markers
The presence of a positive core hepatitis antibody and a negative surface antigen can be indicative of several scenarios in hepatitis B virus (HBV) infection.
- A person who has been infected with HBV in the past and has recovered, as the core antibody (anti-HBc) remains positive even after the surface antigen (HBsAg) has been cleared from the blood 2.
- A person with chronic HBV infection who is in an inactive carrier state, where the virus is not actively replicating and the surface antigen is not detectable, but the core antibody is still present 3.
- A person who has been vaccinated against HBV, as the vaccine only induces the production of surface antibody (anti-HBs) and not core antibody, but in some cases, the core antibody can be detected due to cross-reactivity or other factors 4.
Clinical Implications
The detection of these serological markers is crucial for the clinical classification and epidemiological surveillance of HBV infection.
- The presence of anti-HBc can indicate recent or continued HBV replication, even in the absence of detectable HBsAg 3.
- The level of anti-HBc can also be used as a predictor of treatment response in patients with chronic hepatitis B (CHB) 5.
- Additionally, the correlation between serum HBsAg and anti-HBc levels and liver fibrosis stages in CHB patients has been observed, with higher anti-HBc levels associated with significant fibrosis 6.
Diagnostic Considerations
The diagnosis of HBV infection should be based on the combination of clinical, laboratory, and epidemiological findings.
- The detection of HBsAg and anti-HBc should be interpreted in the context of the patient's clinical history, epidemiological antecedents, and other laboratory results 2.
- The use of a single sample for diagnosis may not be sufficient, as the expression of serological markers can change over time, and multiple samples may be needed to confirm the diagnosis 4.