Hepatitis B Core Antigen Test: What the Result Means

The core antigen is part of the virus. In routine care, clinicians commonly assess the related core antibody rather than looking at core antigen alone. A result cannot by itself show whether infection is recent, ongoing, or resolved. The meaning depends on the pattern of other hepatitis B markers, such as surface antigen, surface antibody, and sometimes viral DNA, together with your symptoms and medical history.

A clinician may also review liver enzymes through a [Liver Function Test](/treatments/diagnostics-and-screening/liver-function-test/). Feeling well does not rule out hepatitis B; some people have no symptoms, while others develop [Fatigue](/symptoms/fatigue/) or [Dark Urine](/symptoms/dark-urine/).

Ask the requesting clinician which marker was measured and how it fits with the rest of your hepatitis B panel. Do not interpret one isolated result as a diagnosis. If the pattern suggests current or previous infection, follow-up may include repeat blood tests, liver assessment, or specialist advice. Until the result is clear, avoid sharing razors or toothbrushes and discuss household or sexual contacts with a clinician. Information about the condition is available under [Hepatitis B](/conditions/hepatitis-b/), and prevention is covered by [Hepatitis B Vaccination](/treatments/preventive-care-and-vaccination/hepatitis-b-vaccination/).

Contact a healthcare professional promptly if you have yellowing of the skin or eyes, very dark urine, marked vomiting, increasing drowsiness, severe abdominal pain, or bleeding that is unusual for you. Seek urgent help for confusion, difficulty staying awake, or rapidly worsening illness. These symptoms need assessment regardless of whether a hepatitis B test result is available.

Which hepatitis B marker was tested, and is any part of the panel still pending? Does my result suggest current infection, past exposure, immunity, or an indeterminate pattern? Do I need liver tests or repeat testing? Should people close to me be tested or vaccinated?