H. Pylori Antibody Blood Test: Normal Ranges, Causes & What Your Results Mean

What Is H. Pylori Antibody?

Helicobacter pylori (H. pylori) is a type of bacterium that infects the lining of the stomach. It is one of the most common bacterial infections worldwide, estimated to affect around 40% of the UK population at some point in their lives. The H. pylori antibody blood test detects immunoglobulin G (IgG) antibodies that your immune system produces in response to an H. pylori infection.

When H. pylori colonises the stomach lining, it can cause chronic inflammation (gastritis), which over time may lead to peptic ulcers, duodenal ulcers, and in rare cases, stomach cancer. The antibody test is a useful screening tool because it indicates whether your body has encountered the bacterium, even if you are not currently experiencing symptoms.

It is important to note that the antibody test shows exposure rather than necessarily an active, current infection. IgG antibodies can persist in the blood for months or even years after successful eradication treatment. For this reason, healthcare providers may use additional tests — such as a urea breath test or stool antigen test — to confirm active infection or verify successful treatment.

Why Is H. Pylori Antibody Tested?

Testing for H. pylori antibodies serves several important clinical purposes:

• Investigating dyspepsia: If you experience persistent indigestion, upper abdominal pain, bloating, or nausea, your GP may order this test to determine whether H. pylori is the underlying cause. NICE guidelines recommend a "test and treat" strategy for patients under 55 with unexplained dyspepsia.
• Peptic ulcer screening: H. pylori is responsible for approximately 80-90% of duodenal ulcers and 60-70% of gastric ulcers. Identifying the infection is a critical first step in treatment.
• Cancer risk assessment: H. pylori is classified as a Group 1 carcinogen by the World Health Organisation. Long-standing infection increases the risk of gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma.
• Iron deficiency anaemia investigation: Unexplained iron deficiency anaemia, particularly in younger patients, may be linked to chronic H. pylori gastritis, which impairs iron absorption.
• Pre-treatment baseline: Before commencing long-term non-steroidal anti-inflammatory drug (NSAID) or aspirin therapy, testing for H. pylori helps reduce the risk of NSAID-related ulcers.
• Family history screening: If you have a first-degree relative who has had stomach cancer, screening for H. pylori may be advisable.

Normal Ranges

H. pylori antibody results are typically reported as positive, negative, or equivocal rather than as a numerical scale. However, many laboratories use a quantitative or semi-quantitative measure expressed in units per millilitre (U/mL).

Result	Value (U/mL)	Interpretation
Negative	< 0.9	No significant antibody detected; H. pylori exposure unlikely
Equivocal	0.9 – 1.1	Borderline result; repeat testing or alternative test recommended
Positive	> 1.1	Antibodies detected; current or past H. pylori infection

Reference ranges may vary slightly between laboratories depending on the assay used. Always interpret your results alongside the specific reference range provided on your lab report. In UK clinical practice, the NHS typically uses the urea breath test or stool antigen test as the first-line investigation, with serology reserved for specific circumstances such as recent proton pump inhibitor (PPI) use or antibiotic therapy, which can produce false negatives on other tests.

What Do Positive H. Pylori Antibody Results Mean?

A positive H. pylori antibody result indicates that your immune system has produced antibodies against the bacterium. This can mean:

• Active H. pylori infection: The most common interpretation, particularly if you have never been treated for H. pylori before. The bacterium may be actively colonising your stomach lining.
• Past infection: IgG antibodies can remain detectable for 12-18 months (and sometimes longer) after successful eradication therapy. A positive result does not necessarily mean current infection.
• Chronic gastritis: Ongoing infection can cause persistent inflammation of the stomach lining, leading to symptoms such as burning pain, nausea, and loss of appetite.
• Peptic ulcer disease: Active infection significantly increases the risk of developing gastric or duodenal ulcers.
• Increased gastric cancer risk: Long-term H. pylori infection is associated with a 2-6 fold increased risk of gastric cancer, particularly in individuals with certain bacterial strains (CagA-positive).
• MALT lymphoma association: A rare but important link exists between chronic H. pylori infection and gastric MALT lymphoma, a type of non-Hodgkin lymphoma.
• Functional dyspepsia: Even without ulceration, H. pylori can contribute to chronic digestive discomfort and impaired gastric motility.

If you receive a positive result and have not previously been treated, your GP will typically recommend eradication therapy — a course of antibiotics combined with a proton pump inhibitor.

What Do Negative H. Pylori Antibody Results Mean?

A negative result generally indicates that you have not been exposed to H. pylori, but there are several considerations:

• No current or past infection: The most straightforward interpretation — your immune system has not encountered the bacterium.
• Early infection: If you have been infected very recently, your body may not yet have produced sufficient antibodies to be detected (the "window period"). Seroconversion typically takes 3-4 weeks.
• Immunosuppression: Individuals with weakened immune systems — whether from medication, disease, or advanced age — may not mount an adequate antibody response, leading to false-negative results.
• Successful eradication: If you have previously been treated for H. pylori and antibody levels have declined below the detection threshold, a negative result may confirm successful treatment.
• Low bacterial load: In some cases, a very low level of H. pylori colonisation may not trigger a detectable antibody response.
• Test limitation: Serology has a sensitivity of approximately 85-95% and specificity of 79-90%, meaning false negatives can occur. If clinical suspicion remains high, your GP may recommend a urea breath test or stool antigen test.

How to Improve Your H. Pylori Status

If you have tested positive for H. pylori antibodies and an active infection is confirmed, the primary goal is eradication of the bacterium. Here are the key steps:

Medical Treatment

• Triple therapy: The standard NHS first-line treatment is a 7-day course of a proton pump inhibitor (such as omeprazole or lansoprazole) combined with two antibiotics (typically amoxicillin and clarithromycin, or metronidazole). Eradication rates are approximately 80-85%.
• Quadruple therapy: If first-line treatment fails, second-line regimens may include bismuth subsalicylate alongside different antibiotic combinations for 10-14 days.
• Confirmation of eradication: NICE recommends a urea breath test at least 4 weeks after completing treatment to confirm the infection has been cleared. Do not rely on repeat antibody testing, as IgG levels decline slowly.

Diet and Lifestyle

• Increase probiotic intake: Yoghurt, kefir, sauerkraut, and other fermented foods may support gut health during and after antibiotic treatment. Some studies suggest Lactobacillus and Saccharomyces boulardii can improve eradication rates and reduce antibiotic side effects.
• Eat cruciferous vegetables: Broccoli, cabbage, and Brussels sprouts contain sulforaphane, which has shown antibacterial activity against H. pylori in laboratory studies.
• Reduce irritants: Limit alcohol, caffeine, spicy foods, and smoking, all of which can aggravate gastric inflammation and slow healing.
• Maintain good hygiene: H. pylori is spread via the faecal-oral or oral-oral route. Hand washing before meals and after using the toilet helps prevent reinfection.
• Manage stress: Chronic stress does not cause H. pylori infection but can exacerbate gastritis symptoms. Regular exercise, adequate sleep, and relaxation techniques can support recovery.
• Consider honey and green tea: Manuka honey and green tea polyphenols have demonstrated modest anti-H. pylori properties in vitro, though they are not substitutes for antibiotic therapy.

When Should You Get Tested?

Consider an H. pylori antibody test if you experience any of the following:

• Persistent upper abdominal pain or discomfort, particularly after eating
• Frequent heartburn, acid reflux, or indigestion that does not respond to antacids
• Unexplained nausea, bloating, or loss of appetite
• A history of peptic ulcers or a family history of stomach cancer
• Unexplained iron deficiency anaemia, especially if you are under 50
• Before starting long-term NSAID or aspirin therapy
• If you have idiopathic thrombocytopenic purpura (ITP), as H. pylori eradication can improve platelet counts

The NHS recommends the "test and treat" approach for patients presenting with dyspepsia who are under 55 and have no alarm features (such as unintended weight loss, difficulty swallowing, or vomiting blood). If alarm features are present, urgent referral for endoscopy is warranted regardless of H. pylori status.

Which Lola Health Tests Include H. Pylori Antibody?

Lola Health offers comprehensive blood testing that can help you understand your digestive and overall health. Our tests that may be relevant include:

• Peak Insights — Our most extensive health panel, covering a wide range of biomarkers for a thorough health overview.
• Vital Check — A detailed wellness assessment including key inflammatory and immune markers.
• Core Health — An essential health check covering foundational biomarkers to monitor your wellbeing.

All Lola Health tests use venous blood draws performed by qualified phlebotomists for medical-grade accuracy. Results are reviewed by GP-certified professionals and delivered with personalised health recommendations.