Hepatitis B core antibody, IgM (Serum/Plasma)

What Does This Test Measure?

IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) appear in the blood shortly after HBV infection begins. They signal an ongoing immune response to the virus, often appearing within weeks of exposure. This test is not used to diagnose chronic HBV infection, as IgM levels typically decline over time as the body clears the virus.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of hepatitis B (e.g., fatigue, jaundice, abdominal pain) or if you’ve been exposed to HBV. It’s also used in screening for acute infection, especially in high-risk groups like healthcare workers, travelers to endemic regions, or individuals with multiple sexual partners.

What Does a Positive Result Mean?

A positive result strongly suggests recent HBV infection. It does not confirm chronic infection, as IgM antibodies may disappear as the body fights the virus. Follow-up tests (like hepatitis B surface antibody or surface antigen tests) may be needed to assess long-term infection status.

What Does a Negative Result Mean?

A negative result means your body either hasn’t been exposed to HBV recently or has already cleared the virus. It doesn’t rule out past infection—you may need other tests to check for immunity or chronic infection.