Helicobacter pylori IgG Antibody (Serum)
This blood test looks for IgG antibodies that your immune system makes in response to Helicobacter pylori, a bacterium that can infect the lining of your stomach.
Detecting H. pylori antibodies can suggest that you have been infected with the bacterium. However, IgG antibodies can stay in your blood for a long time even after an infection has been treated and cleared, so this test cannot always distinguish a current infection from a past one. For that reason, it is often used as a screening tool, with active-infection tests (such as a stool antigen or breath test) used to confirm current infection or a cure.
A positive result means H. pylori IgG antibodies were detected, indicating you have been exposed to the bacterium at some point. Because these antibodies can persist after successful treatment, a positive result does not by itself confirm an active infection. Your clinician may recommend a stool antigen test or breath test to check whether the infection is currently present.
A negative result means no H. pylori IgG antibodies were detected, which makes infection less likely. In someone who has never been exposed, this suggests no infection; however, antibodies may take time to develop, so a recent infection could occasionally be missed.
The expected, normal result is negative (no antibodies detected). Because a positive antibody test cannot separate current from past infection, your clinician will interpret it together with your symptoms and, when needed, a test that detects the active bacterium.
Sources
- H. pylori Infection Tests: MedlinePlus Medical Test
- Helicobacter pylori (H. pylori) Infection: Cleveland Clinic
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.