🩹 Urea Breath Test Simulator

Labeled Urea Drink Ingestion

Patient swallows urea labeled with a carbon isotope tracer.

• ¹³C / ¹⁴C: Isotope used (non-radioactive or trace radioactive)
• ~75 mg: Dose (typical urea tracer dose)
• Yes: Fasting required (improves test accuracy)
• ~minutes: Onset (reaches stomach quickly)

Why labeled urea

Short placeholder: tracer carbon lets us follow urea breakdown in breath.

Bacterial Urease Enzyme Splitting

H. pylori urease hydrolyzes urea into ammonia and carbon dioxide.

• Urease: Enzyme (H. pylori surface/cytoplasmic enzyme)
• NH₃ + CO₂: Products (from one urea molecule)
• Acid buffer: Purpose (ammonia neutralizes stomach acid)
• High: Specificity (few other gastric organisms produce it)

Why urease matters

Short placeholder: urease activity is the biomarker this test detects.

Labeled CO2 Production

Labeled CO2 diffuses into blood and travels to the lungs.

• Bloodstream: Transport (CO2 diffuses across gastric wall)
• Lungs: Destination (exchanged at alveoli)
• 10–30 min: Timing (peak labeled CO2 in breath)
• Mass spec / IR: Detection (measures isotope ratio)

From stomach to breath

Short placeholder: labeled carbon rides blood flow into exhaled air.

Breath Sample Collection

Patient exhales into a bag before and after the urea dose.

• Pre-dose: Baseline sample (measures natural isotope background)
• Post-dose: Test sample (taken at set time points)
• Delta value: Analysis (difference over baseline)
• Yes: Non-invasive (no blood draw needed)

Sampling protocol

Short placeholder: two breath samples bracket the urea challenge.

Positive / Negative Result Interpretation

Elevated labeled CO2 above threshold indicates active infection.

• ~4 delta: Cutoff (per-mil excess over baseline)
• ~95%: Sensitivity (high detection accuracy)
• ~95%: Specificity (low false positive rate)
• Diagnosis & cure check: Use (pre/post-treatment testing)

Reading the result

Short placeholder: high CO2 ratio means urease activity, meaning infection.

Short placeholder: test confirms active H. pylori infection non-invasively.