Do Not Use H. Pylori IgG Serology Alone to Guide Treatment Decisions
If H. pylori IgG serology is positive, you must confirm active infection with either a urea breath test (UBT) or a validated monoclonal stool antigen test before initiating eradication therapy. IgG antibodies persist for years after successful eradication and cannot distinguish between active infection and past exposure 1, 2, 3.
Why IgG Serology Is Unreliable for Treatment Decisions
IgG antibodies remain elevated long after eradication: 65-72% of successfully treated patients remain seropositive for more than 1 year, and antibody titers plateau at approximately 50% of baseline levels even 3.5 years after successful treatment 4, 5.
Serology has no role in determining current infection status: The American College of Gastroenterology explicitly states that serology cannot distinguish active infection from past exposure and should not be used for treatment decisions 1, 2, 3.
False positives are common in previously treated patients: Anyone who received H. pylori treatment in the past will likely test positive on IgG serology despite being cured, making this test useless for determining who needs treatment 5.
Recommended Confirmatory Testing Strategy
First: Confirm Active Infection Before Treatment
Urea breath test (UBT) is the gold standard with sensitivity of 94.7-97% and specificity of 95-100% 1, 2.
Monoclonal stool antigen test is an equally accurate alternative with sensitivity and specificity >90%, particularly useful when patients must continue PPI therapy 1, 2.
Critical Pre-Test Requirements
Discontinue PPIs for at least 2 weeks (preferably 7-14 days) before testing to avoid false-negative results 2, 3.
Discontinue antibiotics and bismuth for at least 4 weeks before UBT or stool antigen testing 3.
Patients should fast for at least 6 hours before breath testing 2.
Important Caveat About PPI Use
- A positive test can be trusted even if the patient is on PPIs, but a negative test cannot 3. PPIs reduce bacterial load and cause false negatives, but they do not cause false positives.
When to Proceed Directly to Treatment vs. Endoscopy
Treat Empirically Without Endoscopy (Age <45, No Alarm Symptoms)
Patients under age 45 without alarm symptoms can be treated empirically after confirming active infection with UBT or stool antigen test 1, 3.
Rule out family history of gastric cancer before treating without endoscopy, even in younger patients 1.
Require Endoscopy Before Treatment (Age ≥45 or Alarm Symptoms)
Patients over age 45 or those with alarm symptoms at any age require endoscopy before treatment to exclude gastric malignancy, as the standardized incidence rate of gastric cancer in those over 45 is 19 per 100,000 for men and 9 per 100,000 for women 1, 3.
Patients with known history of gastric ulcer should be referred for repeat endoscopy with biopsy until healed, as malignancy may be present 1.
Test of Cure After Treatment
Mandatory Confirmation Testing
All patients require test of cure at minimum 4 weeks after completing therapy using UBT or stool antigen test 1, 2.
Never use IgG serology for test of cure—it will remain positive for years regardless of eradication success 1, 2, 6, 4, 5.
Timing and Method
Wait at least 4 weeks after treatment completion to allow gastric mucosa recovery and avoid false-negative results from temporary bacterial suppression 1, 2.
UBT has sensitivity of 94.7-97% and specificity of 95-100% for confirming eradication 1, 2.
In bleeding ulcer cases, delay testing to 4-8 weeks after the bleeding episode 2.
Common Pitfalls to Avoid
Do not initiate treatment based on IgG serology alone—you will treat many patients who were previously cured or never had active infection 3, 5.
Do not use IgG serology to confirm eradication—antibody titers decline slowly over years and 65-72% of cured patients remain seropositive indefinitely 6, 4, 5.
Do not test too soon after treatment—testing before 4 weeks yields unreliable results 1, 2, 3.
Do not continue PPIs during diagnostic testing—they reduce bacterial load and cause false negatives, though a positive test on PPIs can still be trusted 2, 3.