What is the best lab test for Helicobacter pylori (H. pylori) infection?

Best Laboratory Tests for Helicobacter pylori Diagnosis

The 13C-urea breath test (UBT) is the best laboratory test for diagnosing Helicobacter pylori infection due to its high accuracy, with sensitivity of 94-97% and specificity of 95-100%. 1, 2

Non-Invasive Testing Options

Urea Breath Test (UBT)

• UBT using [13C]urea is considered the gold standard for H. pylori diagnosis with excellent sensitivity (94.7-97%) and specificity (95-95.7%) 2
• Detects active infection rather than past exposure, making it valuable for both initial diagnosis and confirmation of eradication 2
• Can be safely used in pregnant women and children (when using 13C rather than 14C isotope) 3

Stool Antigen Test (SAT)

• Laboratory-based monoclonal stool antigen test has diagnostic accuracy equivalent to UBT (sensitivity and specificity approximately 93%) 4, 2
• Only validated laboratory-based monoclonal antibody tests should be used, as rapid in-office tests have limited accuracy 4, 2
• Recommended format is ELISA with monoclonal antibody as reagent 4

Serological Testing

• Serology is less accurate than UBT and SAT with average accuracy of only 78% (range 68-82%) 2
• Cannot distinguish between active infection and past exposure, as antibodies remain elevated for months to years after eradication 1, 2
• Only validated IgG serology tests with accuracy >90% should be considered 4
• Useful in specific situations where other tests might be falsely negative (e.g., recent use of antibiotics or PPIs, ulcer bleeding, gastric atrophy, or malignancies) 4, 2

Important Testing Considerations

Medication Interference

• Proton pump inhibitors (PPIs) should be discontinued at least 2 weeks before testing by UBT, SAT, culture, histology, or rapid urease test to avoid false-negative results 1, 2
• Antibiotics and bismuth products should be stopped at least 4 weeks before testing 2
• If stopping these medications is not possible, validated IgG serology can be performed as it is not affected by local changes in the stomach 4

Post-Treatment Evaluation

• UBT or laboratory-based monoclonal stool antigen test are recommended for confirming eradication 1, 2
• Testing should be performed at least 4 weeks after completion of treatment 1, 2
• Serology should not be used for post-treatment evaluation within 6-12 months as antibodies remain elevated after successful eradication 1, 2

Invasive Testing Options (When Endoscopy is Performed)

• Rapid urease test provides quick results during endoscopy 2
• Histology allows visualization of bacteria and assessment of mucosal damage 2
• Culture permits antimicrobial susceptibility testing, especially valuable after treatment failure 2

Common Pitfalls to Avoid

• Using rapid in-office serological tests due to their limited accuracy 4, 2
• Failing to stop PPIs before testing, which can lead to false-negative results in all tests except serology 2
• Using serology to confirm eradication within 6-12 months of treatment 1, 2
• Using panels of IgG, IgA, and IgM tests which provide no added benefit over validated IgG tests 2

Testing Algorithm

1. For initial diagnosis in primary care: 13C-UBT or laboratory-based monoclonal stool antigen test 4, 2
2. If patient has recently used antibiotics or PPIs: Consider validated IgG serology or wait 2 weeks after stopping these medications 4, 2
3. For confirmation of eradication: UBT or laboratory-based monoclonal stool antigen test at least 4 weeks after treatment completion 1, 2