Hepatitis A Antibody: What Your Result Means

What is Hepatitis A Antibody?

Hepatitis A is a liver virus spread mainly through contaminated food and water. The antibody test comes in two forms: IgM (which appears during a current or recent infection) and IgG (which appears later and remains for life, marking immunity). Testing is used to check immunity before travel or work, and to investigate acute hepatitis symptoms.

Typical reference interval: Reported as positive or negative for IgM and/or IgG. A positive IgG means immune (past infection or vaccination). A positive IgM suggests recent infection and needs prompt clinical attention. Your lab's cutoffs apply.. Laboratories differ — the interval printed on YOUR report always governs.

If your Hepatitis A Antibody is high

Common reasons Hepatitis A Antibody runs above the reference interval:

• Past hepatitis A infection — IgG antibodies persist for life after recovery, conferring immunity
• Hepatitis A vaccination — the vaccine produces protective IgG — a common reason for a positive result
• Recent or current infection — a positive IgM indicates the immune system is actively responding to the virus

If your Hepatitis A Antibody is low

Common reasons Hepatitis A Antibody runs below the reference interval:

• No exposure or vaccination — negative results mean you are not immune and could be vaccinated if at risk
• Early infection — IgM takes time to appear, so very early infection can test negative

Symptoms worth knowing

Hepatitis A often causes no symptoms in children and mild illness in adults. When it does cause symptoms, they include fatigue, nausea, abdominal discomfort, dark urine, and jaundice. The antibody test is what separates recent infection from old immunity.

What usually happens next

1. A positive IgM means recent or current infection — seek clinical care, since hepatitis A needs monitoring and can rarely be severe
2. A positive IgG alone means you are immune — no action needed
3. A negative result with risk factors (travel, certain foods, occupational exposure) means vaccination may be recommended

Frequently asked questions about Hepatitis A Antibody results