Urease Breath Test: Understanding H. pylori Detection

Urea Breath Test (UBT) for H. pylori: Mechanism and Interpretation

Non-invasive, accurate test for active Helicobacter pylori infection.

Principle

H. pylori produces urease → hydrolyzes urea → NH₃ + CO₂. Test uses ¹³C- or ¹⁴C-labeled urea.

Procedure

1. Baseline breath sample.
2. Ingest labeled urea (citrus drink/tablet).
3. Wait 15-30 min (¹³C) or 10-20 min (¹⁴C).
4. Post-dose breath sample.
5. Measure ¹³CO₂/¹²CO₂ ratio (mass spec/IR) or ¹⁴C disintegrations (scintillation).

Interpretation

• Δ¹³C (‰) > cutoff (typically 3-5‰) = positive.
• High sensitivity/specificity (>95%).

Critical Pre-Test Conditions

• Off PPIs 2 weeks (suppress urease → false negative).
• Off antibiotics/bismuth 4 weeks.
• Fast 1-6 hours (water ok).
• No smoking 1 hour prior.

Advantages

• Non-invasive, no endoscopy.
• Detects active infection (not past exposure like serology).
• Monitors eradication (4+ weeks post-treatment).
• Safe in pregnancy (¹³C).

Gold standard for diagnosis and confirmation of cure.