Clinical practice--breath tests

The underlying principle of the two non-invasive radio-labelled urea breath tests is similar. Both are positive when the patient's stomach is colonised by Helicobacter pylori because the organism's urease enzyme splits the orally administered urea isotope to labelled CO2 which is then detected in the expired breath. The tests thus reflect active infection and are ideally suited to monitoring the success or failure of different eradication therapies as well as studying rates of acquisition and re-infection/late recrudescence post treatment. [13C]-urea should always be used in children since it is the stable non-radioactive isotope but the [14C]-urea breath test is suitable for most adults, since the dose of radioactivity is minimal.