Infection Tests

Hepatitis B Panel

Also written as: HBsAg, HBsAb (anti-HBs), HBcAb (anti-HBc), Hep B serology

Three markers that together show hepatitis B infection, immunity from vaccination, or past exposure.

What it measures

Three separate markers in the blood. The surface antigen is a protein from the virus itself, so its presence signals the virus is in the body. The surface antibody is the immune system's protective response, and the core antibody is a marker of exposure to the actual virus, because vaccines do not produce it.

Why a doctor orders it

Ordered to screen for hepatitis B in pregnancy, before medicines that suppress the immune system, when liver tests are unexplained, and to check whether vaccination produced protection. The three markers are read together as a pattern rather than one at a time.

What is generally associated with a higher result

In general terms, a positive surface antigen generally means the virus is currently present, whether recently acquired or long-standing. A positive surface antibody on its own is the typical pattern after successful vaccination. A positive core antibody generally indicates exposure to the real virus at some point in the past, since vaccination alone never produces it.

What is generally associated with a lower result

When all three markers are negative, the general reading is no evidence of current infection, past exposure, or vaccine-induced immunity. Antibody levels from an old vaccination can also fade below detection over the years even though protection often persists.

Everyday things that move this number

Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:

• A hepatitis B vaccine given in the days before the draw, which can make the surface antigen briefly detectable
• Years passing since vaccination, which can let the surface antibody fade below the lab's detection level
• A very recent exposure, which the markers may not yet reflect
• High-dose biotin supplements, which can interfere with some antibody test methods
• Differences between lab methods and sample handling

Questions to take to your appointment

• Which of the three markers were actually included in my panel?
• Does my pattern suggest vaccination, past exposure, or something that needs follow-up testing such as HBV DNA?
• Do I need a hepatitis B vaccine or a booster dose based on this pattern?
• Should household members or close contacts consider testing or vaccination?

Build a printable questionnaire with your own results →

Where to read more

MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .

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