ROSH Gastrointestinal Practice Exam

For a 32-year-old woman with abdominal pain after unprotected intercourse, which antibody indicates acute hepatitis infection?

1. Anti-HBe

2. Anti-HBs

3. Anti-HBc-IgG

4. Anti-HBc-IgM

The correct answer is: Anti-HBc-IgM

In the context of hepatitis infection, particularly when assessing for acute hepatitis, the presence of specific antibodies is crucial for determining the timing and nature of the infection. Anti-HBc-IgM is the antibody that indicates an acute hepatitis infection because it represents the first response of the immune system to the hepatitis B virus (HBV) after infection. When a person is newly infected with HBV, the body starts producing IgM antibodies against the core antigen of the virus, which is labeled as Anti-HBc-IgM. This response occurs relatively early in the infection, making it a marker for acute hepatitis. In contrast, Anti-HBc-IgG arises later and indicates past or chronic infection rather than an acute one. The other antibodies listed provide different information. Anti-HBe indicates a lower level of viral replication but does not specifically indicate an acute infection. Anti-HBs suggests recovery and immunity after infection or vaccination rather than active disease. Therefore, the presence of Anti-HBc-IgM is a key indicator of recent and acute hepatitis, making it the correct answer for identifying acute infection in the scenario presented.