Explanation

Helicobacter pylori IgG: what is measured?

Helicobacter pylori is a bacterium that can live in the stomach lining, often from childhood, and can cause long-lasting inflammation of the stomach or of the first part of the small intestine. The immune system makes IgG antibodies against the bacterium. These remain in the blood for a long time after the bacterium has gone, for example after a course of antibiotics. The test therefore measures whether you have ever been in contact with the bacterium; a stool test or a breath test shows whether the bacterium is there now.

What can it detect?

A current or previous infection with Helicobacter pylori, without distinguishing between the two

Result

What does the result mean?

Positive result

A positive result means that you were infected with the stomach bacterium at some point. The bacterium may still be there now, but it may also have gone, for example after previous treatment; this result cannot tell which. Most people with the bacterium do not notice anything. In some, inflammation of the stomach lining develops, with upper abdominal pain, nausea or quickly feeling full, and about 2 in 10 carriers develop a stomach ulcer at some point. Whether the bacterium is present at this moment is shown by a stool test or a breath test.

Negative result

A negative result makes an infection with the stomach bacterium less likely. The test does miss some infections: in countries where the bacterium is uncommon, such as the Netherlands, the sensitivity is around 76 to 80 percent. With a negative result, stomach complaints often have another cause, such as acid reflux or painkillers such as ibuprofen, naproxen or diclofenac. Unlike a stool or breath test, this result is not disturbed by acid-reducing medicines or antibiotics.

After an abnormal result

With a positive result and stomach complaints, a stool test or a breath test is used to check whether the bacterium is still there now. If so, the GP usually prescribes a 10-day course of two antibiotics and an acid-reducing medicine, followed by a follow-up stool or breath test; an antibody test is not suitable for that check. With a negative result, the GP looks at other causes of the complaints.

Reliability

How reliable is the test?

In studies in countries where the bacterium is uncommon, antibody testing had a sensitivity of 76 to 80 percent and a specificity of 79 to 90 percent, according to the Dutch medical specialists' guideline (FMS) on Helicobacter pylori in children; the certainty of this evidence is very low. A positive result does not tell whether there is an active infection, because the antibodies remain long after an infection. A stool test or a breath test detects the bacterium itself and is therefore better suited to showing a current infection or checking a treatment; in the same guideline, the breath test had a sensitivity of 98 and a specificity of 96 percent.

What can affect the result?

IgG antibodies remain present long after the bacterium has gone; after treatment, a positive result says nothing about its outcome.
The reliability figures come from studies in children and vary widely per test.
When infections are uncommon, as in the Netherlands, some of the positive results are false.
The test does not tell whether stomach complaints are caused by the bacterium.

Who it is for

Who is the test useful for?

Useful for

The result is most informative with persistent or recurrent stomach complaints in someone who has never been treated for the stomach bacterium, and then especially a negative result. After previous treatment, a positive result says nothing, because the antibodies remain. In people without stomach complaints, a positive result says little: most carriers have no symptoms, and whether treatment is then worthwhile has not been established.

How common is it?

An estimated 20 in 100 people in the Netherlands have the stomach bacterium, and about 30 to 35 in 100 of people with stomach complaints; the number is falling. In people who grew up in countries around the Mediterranean, Eastern Europe, the Middle East, Asia, Africa, or Central and South America, this can rise to 75 in 100. Most people with the bacterium have no symptoms.

Huisarts & Migrant (knowledge platform for GPs) and Thuisarts.nl

Drawbacks and risks

A positive result in someone whose bacterium has already gone can lead to an unnecessary course of antibiotics with a chance of side effects.
A positive result without stomach complaints can cause worry and follow-up testing whose benefit has not been established.

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