Explanation

Hepatitis B core antibodies (anti-HBc): what is measured?

Anti-HBc are antibodies against the core protein of the hepatitis B virus. This test measures IgM and IgG together (total anti-HBc). Everyone who has or has had a hepatitis B infection makes these antibodies, and they usually remain detectable for life. A vaccine only contains the surface protein of the virus and therefore does not produce anti-HBc. So the test shows whether you have ever been infected with the virus, not whether the infection is still present; HBsAg is needed for that, and whether you are protected is shown by anti-HBs.

What can it detect?

A past hepatitis B infection, even if it never caused symptoms
Together with HBsAg: a hepatitis B infection that is still present, either recently caught (acute) or lasting (chronic)
Together with anti-HBs: the difference between protection through vaccination and protection through a healed infection

Result

What does the result mean?

Positive result

A positive result means that you have probably been infected with the hepatitis B virus at some point. Anti-HBc alone cannot show whether the infection is over or still present: if HBsAg is also positive, there is an infection at this moment; if HBsAg is negative and anti-HBs is positive, the infection has healed and you are immune. If only anti-HBc is positive (core-only), according to the LCI guideline (RIVM) this is usually an infection from long ago in which the other antibodies have faded, or a falsely positive result; the latter is more often the case in people without risk factors from a country where hepatitis B is rare. Less often it is an infection that has only just healed, or an infection in which HBsAg cannot be detected.

Negative result

A negative result means that no anti-HBc was found: you have probably never had a hepatitis B infection. After successful vaccination, anti-HBc is also negative; so a negative result says nothing about protection, which is shown by anti-HBs. Anti-HBc only appears several weeks after HBsAg, usually around the time symptoms start. A test shortly after a risk contact can therefore still be negative.

After an abnormal result

With a positive anti-HBc, the GP usually has HBsAg and anti-HBs measured to see whether the infection has healed or is still present; with a positive HBsAg, referral to a gastroenterologist or internist follows. With only a positive anti-HBc, according to the LCI guideline (RIVM) further testing is usually not needed, but vaccination is readily considered, and HBV DNA is measured in people with liver disease, HIV or treatment that suppresses the immune system. Hepatitis B is notifiable (group B2) in an acute infection (including IgM anti-HBc) or a chronic infection found for the first time (HBsAg or HBV DNA); a single positive anti-HBc does not fall under this.

Reliability

How reliable is the test?

According to the LCI guideline (RIVM), anti-HBc is a good marker to check whether someone has ever had a hepatitis B infection, and it is not present after vaccination. The test does not say whether the infection is still active or whether you are contagious; HBsAg and, if needed, HBV DNA are measured for that. A single positive result without other positive hepatitis B markers is hard to interpret and can be falsely positive.

What can affect the result?

Shortly after infection, anti-HBc cannot yet be detected; the antibodies only appear several weeks after HBsAg.
Total anti-HBc does not distinguish between a recent and an old infection, nor between a healed and a lasting infection.
A positive result without other hepatitis B markers is more often falsely positive in people without risk factors from a country where hepatitis B is rare.
After a blood transfusion or treatment with immunoglobulins, antibodies from donors can be measured for a while.

Who it is for

Who is the test useful for?

Useful for

Useful if you want to know whether you have ever had hepatitis B, for example if you were born in a country where hepatitis B is common, or if you have taken a risk in the past through sex, shared needles or blood contact. The result also helps with the choice of vaccination, and says a lot in people who are going to receive treatment that suppresses the immune system, because an old infection can then become active again. After a recent risk contact, HBsAg says more, and anyone who only wants to know whether a vaccination has worked needs anti-HBs.

How common is it?

In the Netherlands, about 40,000 people had a hepatitis B infection in 2023; that year, 929 infections were reported, 90 of them acute. How many people have ever had an infection, and therefore have anti-HBc, is not known exactly. It is much more common in people born in a country where hepatitis B is common, such as countries in Asia, Africa and South America.

LCI guideline Hepatitis B (RIVM, reports 2023); Thuisarts.nl

Drawbacks and risks

A positive result can cause worry, while it often fits an old, healed infection or is falsely positive; only additional hepatitis B markers show what the result means.
A negative result shortly after a risk contact can wrongly reassure you.

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