How to Obtain a Urea Breath Test for H. pylori
The ¹³C-urea breath test is the gold standard non-invasive test for H. pylori diagnosis and should be widely available as a central service to primary care practices. 1
Pre-Test Patient Preparation
Critical medication washout periods must be strictly followed to avoid false-negative results:
- Stop proton pump inhibitors (PPIs) for at least 2 weeks before testing, as they reduce bacterial load and cause 10-40% false-negative rates 2
- Discontinue antibiotics and bismuth compounds for at least 4 weeks prior to testing, as these medications temporarily suppress H. pylori and produce false-negative results 2
- Patients must fast for at least 6 hours before the test 2
The most common pitfall is inadequate medication washout—particularly PPIs—which is the leading cause of false-negative results. 2 However, if testing cannot be delayed and the patient was recently on these medications, a positive result remains valid since PPIs and antibiotics cause false-negatives, not false-positives. 2
Test Procedure and Administration
The test exploits H. pylori's abundant urease enzyme production, which hydrolyzes labeled urea into ammonia and CO₂ that can be measured in exhaled breath:
- Administer 75 mg of ¹³C-labeled urea with a test meal to delay gastric emptying and allow even distribution throughout the stomach 2
- Use tablet formulations rather than liquid forms, as tablets avoid interference from urease-producing bacteria in the oropharynx 2
- Collect baseline breath sample before urea administration 3
- Collect second breath sample 10-30 minutes after urea ingestion 2, 3
- Breath samples can be mailed to remote analysis centers for processing 3
Equipment and Analysis Requirements
The test requires specific equipment that determines where it can be performed:
- ¹³C-labeled urea substrate (75-100 mg in tablet or liquid form) 2
- Breath collection containers for capturing exhaled air samples 2
- Analysis equipment: isotope ratio mass spectrometer (IRMS), infrared spectroscopy, or laser-assisted ratio analysis 3
The ¹³C version is strongly preferred over ¹⁴C-urea because it is non-radioactive and safe for children and pregnant women, whereas ¹⁴C involves radiation exposure and should be avoided in these populations. 4, 3
Test Accuracy and Interpretation
The urea breath test demonstrates excellent diagnostic accuracy with sensitivity of 94.7-97% and specificity of 95-95.7% based on analysis of 3,643 patients. 2, 5
- Positive results can be trusted even if the patient was on medications, as PPIs and antibiotics cause false-negatives, not false-positives 2
- False-positive results may occur in patients with achlorhydria or atrophic gastritis due to urease-producing non-H. pylori organisms 2
- In patients with low bacterial load (premalignant or malignant gastric lesions), false-negative results are more common—consider endoscopy with biopsies if clinical suspicion remains high despite negative UBT 2
Access and Availability
Primary care physicians should have access to the ¹³C-urea breath test, ideally provided as a central service to primary care practices. 1 The test is easy to perform, does not require special transport conditions, and is available at reasonable cost, though more expensive than serology. 1
For patients under 40-45 years of age with dyspeptic symptoms but without alarm symptoms (anemia, weight loss, dysphagia, palpable mass, malabsorption), who test positive for H. pylori, treatment can be initiated by primary care physicians without endoscopy. 1 This "test and treat" strategy is particularly useful in young dyspeptic patients, avoiding the need for invasive endoscopy. 4
Post-Treatment Confirmation
The UBT is the gold standard for confirming successful eradication of H. pylori infection, with testing recommended 4-6 weeks after completing treatment to avoid false-negatives. 2, 6