Hepatitis B Core Antibody (IgM) – Serum

This blood test measures markers of the hepatitis B virus (HBV), such as the surface antigen (HBsAg), core antibodies, and surface antibodies. These markers help show whether you currently have an active hepatitis B infection, had one in the past, or are protected through vaccination or recovery from an earlier infection.

The test measures **IgM antibodies** specific to the hepatitis B core protein. When the hepatitis B virus infects your liver, your immune system produces these antibodies as part of its response. Detecting them in your serum suggests an active infection, often occurring within the first few months after exposure.

This test is done to find out whether you have been infected with hepatitis B, to determine whether an infection is new (acute) or long-lasting (chronic), to check whether you have immunity from the hepatitis B vaccine, and to guide decisions about treatment, monitoring, or steps to protect people close to you from getting infected.

Your healthcare provider may order this test if you have symptoms of hepatitis B, such as fatigue, abdominal pain, or jaundice, or if you’ve been exposed to the virus. It can also be used to monitor treatment progress or assess infection spread in certain situations.

A positive result means that hepatitis B virus markers were detected in your blood, which usually points to a current or recent infection. Depending on exactly which markers are positive, your doctor may order additional blood tests to find out whether the infection is acute or chronic, how active the virus is, and whether antiviral treatment or regular follow-up is recommended.

A positive result indicates the presence of IgM antibodies, suggesting an **active hepatitis B infection**. This does not mean you are currently contagious in all cases, but it signals that your body is actively fighting the virus. Further testing may be needed to confirm infection status and guide treatment.

A negative result means that no hepatitis B virus markers were found in your sample, which generally indicates you do not have an active infection. If you were tested soon after a possible exposure, the virus may not yet be detectable, so your doctor may advise repeating the test. A negative result combined with positive surface antibodies usually means you are immune, either from vaccination or from a past infection that has resolved.

A negative result means IgM antibodies were not detected in your serum, which may mean you either have never been infected or have recovered from an acute infection. However, this test alone cannot rule out past infection or chronic hepatitis B, so additional tests may be required.