Helicobacter pylori (H. pylori): Tests and What Positive Means

Gastroenterology

Reviewed by the LabReadAI medical team
Helicobacter pylori (H. pylori): Tests and What Positive Means

"H. pylori positive" — and the immediate question: do I have an ulcer, cancer, must I treat it urgently? Relax. Helicobacter pylori is a very common stomach bacterium carried by a large share of people, and by no means in all of them does it cause disease. But there is an important nuance: different H. pylori tests answer DIFFERENT questions, and a positive blood result is not at all the same as an active infection.

What H. pylori Is and Why It Is Tested

H. pylori is a bacterium that lives in the stomach lining and can cause chronic gastritis, peptic ulcer disease, and in some cases raises the risk of stomach cancer. At the same time many carriers have no symptoms at all. H. pylori is tested for complaints (stomach pain and heaviness, heartburn), with an ulcer, with iron deficiency, and in a number of other situations a doctor determines.

Which Tests Exist (Breath, Stool, Blood, Biopsy)

There are several methods, and they are fundamentally different: the urea breath test, a stool antigen test, antibodies (IgG) in blood, and a biopsy during gastroscopy. The key difference is that some methods show an ACTIVE infection right now, while others show only the fact of contact with the bacterium at some point. Understanding this difference spares needless worry and unnecessary treatment.

Breath Test and Stool Test — for Active Infection

To answer "is the bacterium present now," guidelines recommend the urea breath test or a stool antigen test: their accuracy is high (sensitivity and specificity >95%), and they are used both to confirm infection and to verify the success of treatment after a course of antibiotics. These are the methods of choice for diagnosing active H. pylori.

IgG Antibodies in Blood: What They Show (and Their Limit)

A blood test for IgG antibodies to H. pylori has a serious limitation: it does NOT distinguish a current infection from a past one. Antibodies appear after 2–3 weeks and remain elevated for YEARS even after successful treatment. About half of people with a positive IgG have no active infection. So leading gastroenterology societies no longer recommend serology as a test of active infection and do not use it to confirm cure.

What a Positive H. pylori Means

It all depends on WHICH test is positive. A positive breath test or stool antigen is an active infection, and it is usually treated. But a positive blood IgG on its own may mean only past contact and does not prove the bacterium is present now. More on choosing and preparing for the tests is in the article on H. pylori tests.

How to Prepare and When to See a Doctor

An important detail: proton pump inhibitors (omeprazole and the like), antibiotics and bismuth can give a false-negative breath test, stool test and biopsy — they are usually stopped in advance on a doctor's schedule. See a doctor for persistent symptoms, with an ulcer, with a positive test for active infection, and with iron deficiency (ferritin) of unclear cause. Chronic H. pylori gastritis can impair absorption and lead to vitamin B12 deficiency.

This article is for informational purposes only and does not replace a doctor's consultation.

Frequently asked questions

  • It depends on the test. A positive breath test or stool antigen means an active infection, which is usually treated. A positive blood IgG on its own may indicate only past contact and does not prove an infection now. So it matters which test gave the plus; details are in the article on H. pylori tests.

  • The breath test (and stool antigen test) show an active infection right now and are suitable for verifying cure. The blood IgG antibody test shows only contact with the bacterium and stays positive for years after treatment, so it is suitable neither for confirming active infection nor for follow-up after a course.

  • An isolated positive IgG without a confirmed active infection is not a reason to automatically prescribe antibiotics: about half of people with positive serology have no active infection. To decide whether therapy is needed, a doctor orders a breath test or a stool antigen test.

  • For the breath test, stool test and biopsy it is important to stop in advance the drugs that distort the result: proton pump inhibitors (about 2 weeks before), antibiotics and bismuth (about 4 weeks before) — a doctor sets the exact timing. Not following this is a common cause of a false-negative result.

  • No. H. pylori is very common, and most carriers develop neither an ulcer nor cancer. The bacterium raises the risk of these diseases but does not mean they are present. The decision on treatment and monitoring is made by a doctor, weighing symptoms, results and risk factors, not a single positive test. More on stomach lining inflammation is in the article on gastritis.

#Ferritin#Vitamin B12#Complete Blood Count

For informational purposes only

This article is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Please consult a healthcare professional for medical guidance.

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