Serology for H. pylori: Not Recommended for Routine Diagnosis
Serology testing should not be used for routine diagnosis of H. pylori infection or to confirm eradication after treatment—instead, use urea breath test (UBT) or laboratory-based monoclonal stool antigen test, which detect active infection with approximately 93-97% accuracy. 1, 2
Why Serology Is Inadequate
Serology cannot distinguish between active infection and past exposure because anti-H. pylori IgG antibodies persist in blood for months to years after successful eradication, making it unreliable for confirming current infection status 1, 2, 3
The overall accuracy of commercial ELISA serology tests averages only 78% (range 68-82%), which is inadequate for clinical use on both clinical and economic grounds 2, 3
Serology cannot be used to confirm eradication after treatment since antibody levels remain elevated long after H. pylori elimination 2, 4, 3
The positive predictive value of serology falls dramatically in populations with low disease prevalence, further limiting its clinical utility 2
Preferred Diagnostic Approaches
For Initial Diagnosis (Non-Invasive)
Urea Breath Test (UBT) is the most accurate non-invasive test with sensitivity of 94-97% and specificity of 95-97.7%, detecting active infection by measuring urease activity 2, 4, 3
Laboratory-based validated monoclonal stool antigen test demonstrates sensitivity and specificity of approximately 93%, comparable to UBT, and directly detects H. pylori bacterial antigens in stool specimens 2, 4, 3
Avoid rapid in-office immunochromatographic stool tests due to significantly lower accuracy of 80-81% compared to laboratory-based monoclonal tests 2, 3
For Patients Requiring Endoscopy
Rapid urease test (RUT) has pre-treatment sensitivity of 80-95% with specificity of 95-100%, providing quick results during endoscopy 4, 3
Histological examination with immunohistochemistry is the gold standard among invasive tests, requiring at least two biopsy samples from the antrum and body for improved sensitivity 4, 3
Culture provides definitive proof and allows antimicrobial susceptibility testing, particularly valuable after treatment failure when antimicrobial resistance is suspected 4, 3
Limited Situations Where Serology May Be Considered
Serology is the only test not affected by local gastric changes that could lead to low bacterial load and false-negative results with other tests 2
May be appropriate when patients have recently used antibiotics, bismuth products, or PPIs and medication washout is not possible, though waiting 2-4 weeks after stopping these medications is preferred 2, 3
In patients with gastric atrophy, gastric malignancies, or ulcer bleeding, serology may be more reliable than other non-invasive tests due to patchy distribution of organisms 2
Useful in large epidemiologic surveys and population screening in high-prevalence areas, or studies on age at acquisition of infection 2
Critical Testing Considerations to Avoid False Results
Proton pump inhibitors must be stopped for at least 2 weeks before testing by culture, histology, rapid urease test, UBT, or stool test to avoid false-negative results 1, 2, 4, 3
Antibiotics and bismuth must be discontinued at least 4 weeks before testing to reduce risk of false-negative results 1, 2, 4
For confirmation of eradication, testing should be performed no earlier than 4 weeks after completion of treatment using UBT or stool antigen test, never serology 2, 4, 3
Patients should fast for at least 6 hours before UBT for optimal accuracy 3
Common Pitfalls
False-positive UBT results can occur in patients with achlorhydria (e.g., pernicious anemia or atrophic gastritis) due to overgrowth of non-H. pylori urease-producing organisms 1
When false-positive tests are suspected, confirm UBT result with stool antigen test or endoscopy before giving another course of therapy 1
Avoid using panels of IgG, IgA, and IgM tests as they provide no added benefit over validated IgG tests and may include non-FDA-approved tests of unclear diagnostic value 2
When using large commercial laboratories in the United States, request only FDA-approved tests because commercial laboratories also offer in-house derived tests of unknown specificity and sensitivity 1
Who Should Be Tested
Test patients with active or past peptic ulcer disease, uninvestigated dyspepsia, gastric MALT lymphoma, family history of gastric cancer or peptic ulcer disease, and first-generation immigrants from high-prevalence areas 1, 5
High-risk groups in the United States include Latino and African American populations with 2.6-3.2 fold higher prevalence compared to the general population 1
Test family members residing in the same household of patients with proven active H. pylori infections to prevent person-to-person transmission and protect other members from infection 1