Explanation

Hepatitis A IgG/IgM combi (anti-HAV): what is measured?

The hepatitis A virus causes inflammation of the liver and spreads via stool, for example through contaminated water or food, via the hands or through sexual contact involving the anus. During an infection, the immune system first makes IgM antibodies; according to the LCI guideline (RIVM), these can usually already be detected when the symptoms start, and they then disappear over the course of months. After that come IgG antibodies, which stay for life and go together with protection. This test measures both classes; the laboratory indicates whether the result fits a recent or an older infection.

What can it detect?

A current or recent hepatitis A infection (IgM)
A past hepatitis A infection or protection after vaccination (IgG)

Result

What does the result mean?

Positive result

Antibodies against the hepatitis A virus have been found. What this means depends on the class. If the antibodies are IgM, it is an infection from the past few months: symptoms are then nausea, poor appetite, abdominal pain, fever and often yellowing of the skin and the whites of the eyes. If they are only IgG, you have had the infection at some point or have been vaccinated; you are then protected against a new infection. If only a combined result is reported, that single value cannot show whether it is a recent or an old infection, and the laboratory measures IgM separately. Hepatitis A does not become chronic and almost always heals on its own, although the tiredness can last for weeks to months.

Negative result

No antibodies against the hepatitis A virus have been found. This means you have probably not had the infection and are not (or no longer) vaccinated, so you are not protected. Very early in an infection the result can still be negative, although according to the LCI guideline (RIVM) IgM antibodies are usually already present as soon as the symptoms start. With ongoing symptoms that fit an inflammation of the liver, further tests are needed, even with a negative result.

After an abnormal result

If there are signs of a current infection, the doctor measures the liver values and assesses whether further tests are needed; there is no specific treatment, and the infection clears up on its own. Household members and other contacts can get vaccinated via the GGD (municipal public health service) to prevent spread. Hepatitis A is notifiable (group B2): a confirmed infection is reported to the GGD within one working day.

Reliability

How reliable is the test?

According to the LCI guideline (RIVM) on hepatitis A, IgM against the hepatitis A virus can usually already be detected as soon as the symptoms start, so the test gives a good indication when there are symptoms of liver inflammation. The guideline does warn that relying on IgM alone has risks, because the sensitivity and specificity of a test are rarely 100 percent; if in doubt, further tests follow, such as a PCR on stool or blood. Serology cannot tell whether protection comes from a past infection or from vaccination. The result is always assessed together with the symptoms and the liver values.

What can affect the result?

IgM can stay positive for months after the infection and then suggest a recent infection that is no longer there.
A falsely positive IgM does occur; if in doubt, a PCR is needed.
The antibodies alone cannot show whether protection comes from a past infection or from vaccination.
After immunoglobulins have been given, antibodies from donors can temporarily be measured as well.

Who it is for

Who is the test useful for?

Useful for

Useful with symptoms that fit an inflammation of the liver, such as yellowing of the skin or the whites of the eyes, nausea, poor appetite and dark urine, especially after travel or contact with someone with hepatitis A. Also useful before a vaccination to check whether someone is already protected, for example in people who grew up in an area where the virus is common; they have often had the infection as a child. In people without symptoms and without a travel or vaccination question, the result changes little.

How common is it?

Between 2013 and 2022, 50 (in 2020) to 373 (in 2017) cases of hepatitis A were reported each year in the Netherlands, which comes to 0.3 to 2.1 per 100,000 inhabitants. The infection is often caught during travel to an area where the virus is common. Children younger than 5 usually have no symptoms; the older someone is, the more often the infection causes symptoms.

LCI guideline (RIVM) on hepatitis A (reports 2013 to 2022)

Drawbacks and risks

A falsely positive IgM can lead to unnecessary follow-up tests, a report to the GGD (municipal public health service) and measures for household members that turn out not to have been needed.
A result that does not show IgM and IgG separately can wrongly give the impression of a recent infection, when it is actually protection from long ago or after vaccination.

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