Helicobacter pylori is one of the most common causes of chronic bacterial infection in humans, and is associated with many diseases of the upper gastrointestinal tract. The prevalence of infection rises with age, and in most cases colonisation probably begins during childhood.1 The modes of acquisition of infection and the evolution of disease associations must therefore be studied in childhood, which means that reliable non-invasive diagnostic techniques are required. The most widely used minimally invasive tool is IgG serodiagnosis, and although this does perform well among adults and older children with established infection, it may not be accurate in younger children.2 Stable isotope techniques may therefore prove to be more useful in early life.

In order to investigate the use of stable isotope techniques for diagnosing H pylori infection, particularly in childhood, a group of collaborators throughout Europe was established under the BIOMED initiative. The principal aims of this group were:

• To assess the performance of stable isotope tests of gastric urea hydrolysis in clinical practice as diagnostic tools forH pylori colonisation, and to evaluate protocols for their application in childhood

• To define the role of these tests as tools in clinical practice and in epidemiological studies in childhood.

The progress made in achieving these aims is summarised in this short review and in the following abstracts.

Two stable isotope substrates are available to look at urea hydrolysis—¹⁵N urea and ¹³C urea. Tests using these rely upon gastric hydrolysis of labelled urea by H pyloriurease, and subsequent recovery of label in expired CO₂ or urinary nitrogen. Although ¹⁵N urea urine tests have been described,3 there is little experience of their use in childhood. The group working in Leipzig have shown that this non-invasive test is acceptable among young children, and …