From the Guidelines
The primary laboratory test ordered to screen for hepatitis B infection is the hepatitis B surface antigen (HBsAg) test. This test detects the presence of the viral protein on the surface of the hepatitis B virus, which appears in the blood during active infection [ 1 ]. A positive HBsAg result indicates current hepatitis B infection, either acute or chronic. For a more comprehensive assessment, healthcare providers often order a hepatitis B panel, which includes additional tests such as hepatitis B surface antibody (anti-HBs), hepatitis B core antibody (anti-HBc), hepatitis B e antigen (HBeAg), and hepatitis B e antibody (anti-HBe). These additional markers help determine whether the infection is acute or chronic, the stage of infection, and whether the person has immunity from past infection or vaccination [ 1 ].
Some key points to consider when interpreting HBsAg test results include:
- A positive HBsAg result indicates current hepatitis B infection [ 1 ]
- HBsAg appears in the blood during active infection, typically 1-10 weeks after exposure [ 1 ]
- The combination of HBsAg quantification and HBV DNA level is an integral component of monitoring the response to antiviral therapy [ 1 ]
- Serologic tests, including anti-HBs and anti-HBc, can assist in screening of populations for HBV infection and differentiating among acute, chronic, and past infections [ 1 ]
Screening is particularly important because many people with hepatitis B remain asymptomatic while the virus can still cause progressive liver damage and increase the risk of liver cancer [ 1, 1 ]. Therefore, the HBsAg test is a crucial tool for identifying individuals with hepatitis B infection and preventing further transmission and complications.
From the Research
Laboratory Tests for Hepatitis B Infection
The laboratory test ordered to screen for hepatitis B infection is the detection of hepatitis B surface antigen (HBsAg) [ 2, 3,4,5,6] ].
- HBsAg is a key marker for screening and laboratory diagnosis of HBV infection.
- Rapid diagnostic tests (RDTs) for HBsAg detection are simple, fast, and cheap, making them a powerful tool for large-scale screening and diagnosis of HBV infection.
- The sensitivity and specificity of HBsAg detection vary among different tests and brands, but overall, HBsAg RDTs have good sensitivity and excellent specificity compared to laboratory immunoassays as a reference standard 5.
- Other serological markers, such as IgM and IgG antibodies to hepatitis B virus core antigen (anti-HBcIgM and anti-HBcIgG), are also important for the clinical classification and epidemiological surveillance of HBV infection 4.
- The detection of HBsAg and anti-HBcIgM is used in the diagnosis of acute hepatitis B virus infection after recent exposure 6.