Hydrogen breath test: what it is used for and how it is performed

By Cristiano Antonino On Jan 12, 2023

The H2-breath test is a quick and painless test useful for diagnosing the presence of Helicobacter Pylori, the bacterium responsible for many cases of gastritis

The test is performed in cases of suspected gastro-duodenal ulcers or in the presence of epigastralgia, and is often performed after the patient has undergone eradicating antibiotic therapy to see if the bacterium has been eliminated.

What the Hydrogen breath test consists of

Helicobacter Pylori is a microorganism that adheres to the gastric mucosa and survives gastric acidity because it possesses urease, an enzyme that breaks down urea into carbon dioxide (CO2) – absorbed and eliminated through the lungs – and ammonia.

Normally urease is not present in the body, so ingested urea is disposed of in the urine.

The Hydrogen breath test is based on this very process

The patient takes urea containing the (non-radioactive and harmless) carbon isotope 13C orally.

If present, Helicobacter Pylori breaks down the urea by producing CO2 with traces of the isotope; the ‘labelled’ carbon dioxide ends up in the area exhaled from the lungs, which can be analysed for the presence of urease in the body and thus the bacterium.

The patient must therefore first blow all the air in his lungs into a vial (sampling of basal exhaled air), then ingest a tablet of Urea labelled with the 13C isotope (dissolved in a drink) and – after waiting about 30 minutes – blow more air into a new vial.

The presence of Helicobacter Pylori is diagnosed if there is an increase in 13C in the air exhaled after ingestion of the tablet.

The test has no contraindications, is simple to perform and has a good sensitivity and specificity.

Helicobacter Pylori: How To Recognise And Treat It

Intestinal Infections: How Is Dientamoeba Fragilis Infection Contracted?

Ascaridiasis: What It Is And What The Symptoms Are